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Biomedical subjects

Y Omura

Publications and source records attributed to Y Omura.

At least 19 recordsLinked to original sources
PubMed2001

Conjugated linoleic acid accumulation via 10-hydroxy-12-octadecaenoic acid during microaerobic transformation of linoleic acid by Lactobacillus acidophilus.

Specific isomers of conjugated linoleic acid (CLA), a fatty acid with potentially beneficial physiological and anticarcinogenic effects, were efficiently produced from linoleic acid by washed cells of Lactobacillus acidophilus AKU 1137 under microaerobic conditions, and the metabolic pathway of CLA production from linoleic acid is explained for the first time. The CLA isomers produced were identified as cis-9, trans-11- or trans-9, cis-11-octadecadienoic acid and trans-9, trans-11-octadecadienoic acid. Preceding the production of CLA, hydroxy fatty acids identified as 10-hydroxy-cis-12-octadecaenoic acid and 10-hydroxy-trans-12-octadecaenoic acid had accumulated. The isolated 10-hydroxy-cis-12-octadecaenoic acid was transformed into CLA during incubation with washed cells of L. acidophilus, suggesting that this hydroxy fatty acid is one of the intermediates of CLA production from linoleic acid. The washed cells of L. acidophilus producing high levels of CLA were obtained by cultivation in a medium containing linoleic acid, indicating that the enzyme system for CLA production is induced by linoleic acid. After 4 days of reaction with these washed cells, more than 95% of the added linoleic acid (5 mg/ml) was transformed into CLA, and the CLA content in total fatty acids recovered exceeded 80% (wt/wt). Almost all of the CLA produced was in the cells or was associated with the cells as free fatty acid.

Aerobiosis↗
PubMed2000

Immunocytochemical localization of taurine in the fish retina under light and dark adaptations.

Previously we have observed the lack of immunoreactivity of taurine in the rod outer segments from light-adapted fish, such as the ayu Plecoglossus altivelis and lefteye flounder Paralichthys olivaceus. This finding prompted us to investigate if there is a difference in the immunocytochemical localization of taurine in the rod outer segments between the dark- and light-adapted states. In the retinas of the glass eel Anguilla japonica and the young goldfish Carassius auratus, extremely intense immunostaining was found in the cone outer segments, rod inner segments, photoreceptor supranuclear region and outer plexiform layer. The rod outer segments were not immunostained in the light-adapted state, while they were intensely immunostained in the dark-adapted state. Consequently, it was suggested that the lack of immunoreactivity in the rod outer segment may depend on light stimulation. In addition, the conspicuous immunocytochemical localization of taurine was discussed with the possible functional roles for taurine in the fish retina.

Adaptation, Physiological↗
PubMed2000

Development of a novel enzyme-linked immunosorbent assay for blood and urinary eosinophil-derived neurotoxin: a preliminary study in patients with bronchial asthma.

BACKGROUND: Eosinophil-derived neurotoxin (EDN), also called eosinophil protein X (EPX), has been suggested to be a useful marker of eosinophilic inflammation. However, no commercial enzyme-linked immunosorbent assay (ELISA) kit for EDN is available yet. METHODS: EDN was purified from pooled urine from healthy male volunteers. Polyclonal and monoclonal anti-EDN antibodies were subsequently raised, and a sandwich ELISA for EDN was established. EDN levels in serum, plasma and urine from asymptomatic patients with bronchial asthma were measured by the ELISA method. Some of the blood samples were also measured by a commercial radioimmunoassay (RIA) kit. RESULTS: The ELISA method detected human EDN with a minimum detection limit of less than 0.62 ng/ml and did not cross-react with other eosinophil granule cationic proteins including eosinophil cationic protein. The intra- and interassay coefficients of variation of the ELISA method ranged from 2.6 to 3.6% and from 6.5 to 9.4%, respectively. Good linearity was observed with serially diluted different samples, and the recoveries of the purified EDN added to serum samples ranged from 85 to 110%. Median EDN concentrations in serum (36.9 vs. 19.1 ng/ml), plasma (23.0 vs. 14.5 ng/ml) and urine (118.2 vs. 72.1 microg/mmol Cr) were significantly raised in asymptomatic asthmatic patients compared with healthy control subjects. EDN levels in serum, plasma and urine from the patients significantly correlated with the number of peripheral blood eosinophils, but not total serum IgE levels. A significant relationship between EDN values measured by the EPX-RIA kit and the EDN-ELISA method was observed. CONCLUSIONS: We have developed a novel efficient ELISA method to specifically measure blood and urinary EDN, which may be useful to study the role of eosinophils in allergic diseases including bronchial asthma.

Asthma↗
PubMed1999

Gastric cancer with sarcoid reactions in the regional lymph nodes, the stomach wall, and the splenic parenchyma: report of a case.

A 66-year-old man was referred to our institute for investigation of heartburn and epigastralgia. Endoscopic examination demonstrated a type 4' gastric cancer which occupied the whole stomach. At laparotomy, multiple small nodules were found in the spleen which were diagnosed as metastases of the gastric cancer. Thus, total gastrectomy with distal pancreatectomy, splenectomy, cholecystectomy, and left adrenalectomy, combined with D4 lymph node dissection, was performed. Microscopic examination of the tumor revealed tubular and mucinous adenocarcinoma which invaded the muscularis propria. Sarcoid reactions were observed in the submucosa adjacent to the carcinoma tissue. Only one lymph node from station no. 8a demonstrated tumor metastasis, while those from station nos. 1, 2, 7, 8, 9, 10, 11, 13, and 16 revealed sarcoid reactions without tumor metastases. Subsequently, the multiple small nodules that had been presumed to be splenic metastases at laparotomy were found to be sarcoid reactions similar to those seen in the submucosa and regional lymph nodes. Since no skin or ocular lesions indicative of systemic sarcoidosis were seen in this patient, a diagnosis of advanced gastric cancer associated with sarcoid reactions was established. To our knowledge, there have been no previous reports regarding an association between sarcoid reactions in the spleen and gastric cancer.

Adenocarcinoma, Mucinous↗
PubMed1999

Immunocytochemical localization of taurine in the developing retina of the lefteye flounder Paralichthys olivaceus.

Light microscopic immunolocalization of taurine, a sulfur-containing free amino acid, was investigated in the developing retina of a lefteye flounder, Paralichthys olivaceus, which exhibits metamorphic changes with rod cell addition for 3-5 weeks after hatching. This immunocytochemical study of the developing retina revealed: 1) From 3 to 13 days after hatching, intense immunostaining was shifted from the surroundings of neural cells to the neural somata and processes in the inner retina. 2) Intense immunoreactivity appeared also in the outer and inner segments and basal processes (pedicles) of cone cells within 6 days or 13 days after hatching. 3) Lack of immunoreactivity was found in the outer segment of rod cells from their appearance during metamorphosis. These findings are discussed with the possible functional roles of taurine in the fish retina: 1) involvement in cell differentiation and/or development; 2) protection of the outer segments against light stimuli; and 3) regulation of neural transmission.

Age Factors↗
PubMed1998

Embryonic development of the inner ear and otolith of the rainbow trout Oncorhynchus mykiss.

The embryonic development of the inner ear, especially the sensory epithelia and otoliths in the rainbow trout Oncorhynchus mykiss, was studied by light and electron microscopy. Light microscopically, the auditory vesicle, saccular otolith and statoacoustic ganglion were first observed by 12 days after fertilization, while the utricular otolith appeared at 15 days after fertilization. Both the saccular and utricular maculae were more developed at 22 days after fertilization, and well developed by 27 days. The crista ampullaris of the horizontal canal was also developed at 27 days after fertilization, while the other cristae were not yet distinguished. Electron microscopically, vesicular structures and short microvilli were found on the sensory epithelia of the maculae by 15 days after fertilization. At 22 days after fertilization, the saccular otolith possessed 7 incremental layers, and developing cilia, microvilli, and aggregates of secretory materials also appeared on the apical surface of the sensory epithelia. At 27 days after fertilization, the apical surface of each hair cell was covered with a hair bundle consisting of a single kinocilium and a bundle of stereocilia. These findings are discussed with special regard to the environmental factors on early development in fishes.

Animals↗
PubMed1998

Estimation of the amount of telomere molecules in different human age groups and the telomere increasing effect of acupuncture and shiatsu on St.36, using synthesized basic units of the human telomere molecules as reference control substances for the bi-digital O-ring test resonance phenomenon.

It is well established that the telomeres at the ends of chromosomes are composed of long arrays of (TTAGGG)n x (CCCTAA)n that form a nucleoprotein complex required for the replication and protection of chromosome ends. Throughout the cell cycle, telomeres also contain a protein component related to the proto-oncogene Myb that is known as TRF1 (telomere TTAGGG repeat binding factor 1) that binds to the duplex array of TTAGGG repeats in the telomere. Previous studies have shown that TRF1 appears to play a role in controlling the length of telomeres by acting as an inhibitor of telomerase. The amount of each of the TRF1(C-19) & TRF1(N-19) was identical to the amount of telomere of the same organ of the same apparently normal individual. Using synthesized basic unit of TTAGGG, as well as CCCTAA, as separate reference control substances for the Bi-Digital O-Ring Test of Resonance Phenomenon between 2 identical substances, we were able to non-invasively measure the approximate amount of TTAGGG and CCCTAA units, in both normal and cancerous human cells. We examined about 30 apparently normal subjects (both Asian and Caucasian in both sex). The subjects' ages ranged from infancy to 76 years. Each subject was first examined using TTAGGG as a control substance and then examined using CCCTAA as a control substance. The amount of telomere in various cancer tissues are almost always higher than that of normal tissue of the same organ. The measured amounts of both TTAGGG and CCCTAA were found to be in an average of 1500-1600 ng for human fetus or infancy and decreased with the advance of age in both sex with the exception of the heart, brain, eyes (retina), testes, and ovaries, which usually remain at the level of the infant, or reduced very little. Individuals in the same age group had a similar range of amounts of both TTAGGG and CCCTAA in the same organ of the same individual, (except for those with unusually low telomeres often had chronic degenerative diseases, and those who had exceptionally high telomere levels often had excellent physical conditions or mental acumen). The amounts of measured TTAGGG and CCCTAA molecules before and after acupuncture on St. 36 in adenocarcinomas and small cell carcinoma coexisting in the lung of a 54-yr.-old Asian male were: telomere in adenocarcinoma decreased from 950 ng to 750 ng and telomere in small cell carcinoma decreased from 770 ng to 600 ng. When the cancer treatment is effective, the amount of telomere is reduced towards the value of the normal internal organ. We found that acupuncture on St.36 on apparently normal subjects increased the telomere levels up to a maximum of more than 2 times their telomere levels prior to the treatment, depending on the method of treatment, but frequently increases were between 60% to 100%. Strong Shiatsu performed on St. 36 produced a somewhat lesser effect than acupuncture. We also determined the amounts of TTAGGG and CCCTAA molecules non-invasively in 3 mummified Egyptian sisters from the 8th Century BC on exhibit at the Museo Egizio in Turin, Italy in order to estimate their approximate ages (at the time of death). The amounts of body telomere were 500 ng, 550 ng, and 750 ng. For the prehistoric Iceman (about 3350 B.C. to 3310 B.C) discovered in 1991 in the Italian Otzal Alps at about 3,200 meters altitude, estimated body telomere was about 400 ng and telomere in brain and heart was 1600 ng, similar to that of a contemporary human being. Although these studies are preliminary, the findings may have potential applications not only in anti-aging, cancer treatments, and pathophysiology of brain and heart, but also for the estimation of the difference in the ages of cadavers studied in archeology and forensic medicine.

Acupressure↗
PubMed1997

Immunocytochemical localization of taurine in the pineal organ and retina of an anadromous fish, Plecoglossus altivelis.

Light and electron microscopic immunolocalization of taurine, a sulfur-containing free amino acid, was investigated in the photoneuroendocrine pineal organ and the retinal photoreceptor and pigment epithelial layer of the ayu Plecoglossus altivelis, an anadromous fish. Intense immunostaining was found in the outer segments of pineal photoreceptors and retinal cone-like cells. Moderate but definite immunostaining was found in the cytoplasmic processes of pineal supporting cells, the outer segments of retinal rod-like cells, and the apical processes of pigment epithelial cells. Although the electron microscopic immunogold labeling was not completely coincident with the results of light microscopic immunostaining, concentrated immunogold particles appeared in the inner segments of photoreceptor cells, the cytoplasmic processes of pineal supporting cells, and the apical processes of pigment epithelial cells. These light and electron microscopic findings in taurine immunolocalization were discussed in relation to the functions of taurine known mainly from retinal physiology. It was suggested that the abundant taurine localization may be involved at least in the protection of photoreceptor outer segments against harmful factors, and in the transportation of nutrients and metabolites. The immunostaining for taurine is useful for the discrimination of different types of photoreceptor cells in the pineal organ and retina of fish.

Animals↗
PubMed1997

Scanning and transmission electron microscopic study on a multilayered basement membrane in the pineal organ of the ayu Plecoglossus altivelis.

The pineal organ possesses highly fenestrated capillaries, and is devoid of the so-called blood-brain barrier. The present study indicated that the pineal epithelium of the teleost fish, ayu Plecoglossus altivelis, possesses an unusually thick and convoluted basement membrane (2.2-2.4 microm in width) which is visible even under the light microscope. This pineal basement membrane was observed by scanning and transmission electron microscopy and its detailed composition and relationships with the fenestrated capillaries and the perivascular space were investigated. As the basement membrane was composed of three to eight layers of basal laminae interspersed with laminae lucidae, we termed it the "multilayered basement membrane". In consideration of our previous demonstration that macromolecules such as HRP are trapped by the basement membrane, it is suggested that this multilayered basement membrane may prevent foreign substances from reaching the pineal epithelium.

Animals↗
PubMed1997

Impression on observing psychic surgery and healing in Brazil which appear to incorporate (+) qi gong energy & the use of acupuncture points.

In December, 1995, the author had the opportunity to observe an elderly psychic healer of East European origin in Sao Paulo, Brazil. This man specialized in cancer treatment by pointing with the fingers of his right hand at his patients, without actually touching them, spending an average of 30 to 40 minutes with each one. The author considered this to be Qi Gong treatment. In March, 1997 the author also observed 2 leading psychic healers in Brazil. One of them, named Rubens Farias, Jr. is a 43 year-old former engineer and computer programmer if European descent, who is commonly known as "Dr. Fritz III" because he is believed to be the spirit of Dr. Adolf Fritz, a German physician who died during World War I, operates through him. The other is "Dr." Hirota, a 53 year old former farmer of Japanese decent who lives near Campinas. About 120 kilometers outside of Sao Paulo and treats large numbers of people daily using indirect and/or hand-on healing techniques. On March 6, 1997, when the author visited "Dr. Fritz III"'s clinic in Sao Paulo with a group of Brazilian physicians, he was informed the about 1,400 patients had come that day. "Dr Fritz III" examined and treated the majority of the patients in less than one minute each, often asking very quick questions and then immediately beginning treatment. Most patients received injections of a dark-brown solution, which, some of the visiting doctors speculated, may be an iodine solution mixed with either alcohol or a local anesthetic. In many patients, he injected this solution near the pathological area or at an acupuncture point near the pathological area. When the needle of the syringe was in the acupuncture pint, he twirled it with his fingers several times and the withdrew it. Minor surgery was performed in about 1/5th of the patients with whom the author observed. Most of the surgical incisions were made on the midline of the tissue over the spine near the pathological area. The clamping of the blood vessels and the closings of the surgical wounds were performed by licensed surgeons or licensed nurses. Major surgery were done by "Dr. Fritz III" who used a rather primitive and unorthodox cutting technique. Except for major surgery, assistance was performed by volunteer nurses, including his wife. After the surgical wounds were closed, gauze band-aids were applied. When the surface of the gauze facing the wound was examined, it showed strong (+) Qi Gong energy according to the Bi-Digital O-Ring Test. Essentially, "Dr. Fritz III"'s treatment consists of acupuncture, injection of iodine with other substances near the pathological area, and (+) Qi Gong energy stored gauze which is applied to the acupuncture point, pathological area, or the site of surgery. "Dr." Hirota is another famous psychic healer whom the author was able to meet and observe in practice while in Brazil. "Dr." Hirota has been practicing for over 20 years. He usually sees patients who come to his clinic in the mornings and he claims to treat 1,000 to 2,000 patients daily between 9 AM and 12 noon. His main treatment also appears to be the application of external Qi Gong energy through the fingers of his right-hand, in combination with Shiatsu Massage and a manual procedure resembling chiropractic manipulation.

Acupuncture Points↗
PubMed1995

Inhibitory effect of NaCl on hog kidney mitochondrial membrane-bound monoamine oxidase: pH and temperature dependences.

For a further understanding of the inhibitory effect of NaCl on hog kidney mitochondrial monoamine oxidase (MAO), the activity for benzylamine as substrate was assayed spectrophotometrically in the absence and presence of NaCl for mitochondrial outer membrane preparations as well as whole mitochondria. The effect of CaCl2 was also examined for comparison. The inhibition by NaCl but not CaCl2 was strongly pH dependent. The pH dependence of the inhibitory effect of NaCl in phosphate buffer was parallel to the pH dependence of the MAO activity itself. The point at which the slope of the Arrhenius plot in the absence of NaCl decreases with increasing temperature was to be 32.3 degrees C at pH 7.0 and 30.4 degrees C at pH 7.5 in phosphate buffer, while the Arrhenius plot in the presence of NaCl exhibited discontinuities without change in the slope in small temperature ranges, 39.2 degrees C-40.0 degrees C and 33.0 degrees C-34.2 degrees C. It was estimated that the inhibitory effect of NaCl was due to a pH and temperature sensitive cooperative state change involving MAO protein and boundary lipids, while the effect of CaCl2 could be induced by specific Ca2+ binding to acidic phospholipids.

Animals↗
PubMed1994

Outcome of peristomal skin management by long-term use of skin barrier.

Peristomal skin status was retrospectively evaluated in group of patients who routinely used skin barriers as a part of their pouching system. Three hundred forty-four photographs were obtained for 113 patients who used skin-barrier products continuously for periods ranging from 1 to 10 years. Changes in the peristomal skin were evaluated according to severity and three qualitative characteristics: inflammatory changes, pigmentary alterations, and macroscopic evidence of relief from the chronic effects of skin barrier. Of the 344 photographs reviewed, only 7.4% were free from any skin change. The incidence of inflammatory change peaked at 38% before 3 months and varied from 5% to 20% after this riod. The incidence of pigmentary change was 86% at 9 months after operation and 85% to 95% during later periods. Macroscopic evidence of skin relief was observed in 75% to 95% of the photographs across time. This investigation demonstrates that peristomal skin changes among patients who use skin barriers as a routine part of the pouching procedure are dynamic and complex. These products exhibit both skin-protective and skin-irritating properties.

Adult↗
PubMed1993

Early development of the pineal photoreceptors prior to the retinal differentiation in the embryonic rainbow trout, Oncorhynchus mykiss (Teleostei).

The development of the pineal and retinal photoreceptors in the embryonic rainbow trout, Oncorhynchus mykiss was investigated by means of light and electron microscopy. The pineal photoreceptors endowed with photoreceptive outer segments and signal-transmitting synapses appeared first 15 days after fertilization, and well developed by 21 days. In contrast, the retinal photoreceptors appeared as late as 27 days after fertilization (1 day before hatching). This temporal disparity in photoreceptor development has been compared with the photoperiodic formation of otolith increments, which is initiated during an early developmental stage lacking retinal photoreception. It has been suggested that the early development of pineal photoreceptors may be involved in light-dark recognition, establishment of the diel and circadian rhythms, and entrainment to the environmental photoperiod in the embryonic rainbow trout.

Animals↗
PubMed1992

Common factors contributing to intractable pain and medical problems with insufficient drug uptake in areas to be treated, and their pathogenesis and treatment: Part I. Combined use of medication with acupuncture, (+) Qi gong energy-stored material, soft laser or electrical stimulation.

Most frequently encountered causes of intractable pain and intractable medical problems, including headache, post-herpetic neuralgia, tinnitus with hearing difficulty, brachial essential hypertension, cephalic hypertension and hypotension, arrhythmia, stroke, osteo-arthritis, Minamata disease, Alzheimer's disease and neuromuscular problems, such as Amyotrophic Lateral Sclerosis, and cancer are often found to be due to co-existence of 1) viral or bacterial infection, 2) localized microcirculatory disturbances, 3) localized deposits of heavy metals, such as lead or mercury, in affected areas of the body, 4) with or without additional harmful environmental electro-magnetic or electric fields from household electrical devices in close vicinity, which create microcirculatory disturbances and reduced acetylcholine. The main reason why medications known to be effective prove ineffective with intractable medical problems, the authors found, is that even effective medications often cannot reach these affected areas in sufficient therapeutic doses, even though the medications can reach the normal parts of the body and result in side effects when doses are excessive. These conditions are often difficult to treat or may be considered incurable in both Western and Oriental medicine. As solutions to these problems, the authors found some of the following methods can improve circulation and selectively enhance drug uptake: 1) Acupuncture, 2) Low pulse repetition rate electrical stimulation (1-2 pulses/second), 3) (+) Qi Gong energy, 4) Soft lasers using Ga-As diode laser or He-Ne gas laser, 5) Certain electro-magnetic fields or rapidly changing or moving electric or magnetic fields, 6) Heat or moxibustion, 7) Individually selected Calcium Channel Blockers, 8) Individually selected Oriental herb medicines known to reduce or eliminate circulatory disturbances. Each method has advantages and limitations and therefore the individually optimal method has to be selected. Applications of (+) Qi Gong energy stored paper or cloth every 4 hours, along with effective medications, were often found to be effective, as Qigongnized materials can often be used repeatedly, as long as they are not exposed to rapidly changing electric, magnetic or electro-magnetic fields. Application of (+) Qi Gong energy-stored paper or cloth, soft laser or changing electric field for 30-60 seconds on the area above the medulla oblongata, vertebral arteries or endocrine representation area at the tail of pancreas reduced or eliminated microcirculatory disturbances and enhanced drug uptake.(ABSTRACT TRUNCATED AT 400 WORDS)

Acupuncture Therapy↗
PubMed1992

Bi-directional transmission of molecular information by photon or electron beams passing in the close vicinity of specific molecules, and its clinical and basic research applications: 1) Diagnosis of humans or animal patients without any direct contact; 2) Light microscopic and electron microscopic localization of neuro-transmitters, heavy metals, Oncogen C-fos (AB2), etc. of intracellular fine structures of normal and abnormal single cells using light or electro-microscopic indirect Bi-Digital O-Ring Test.

In 1985, Omura, Y. discovered that, when specific molecules were placed anywhere in the close vicinity of the path of a light beam (laser), their molecular information, as well as information on electrical & magnetic fields, is transmitted bi-directionally along the path of this light beam. Namely, this information is transmitted in the direction the light beam is projected and towards the direction from which the light beam is coming. This finding was applied to the following clinical and basic research: 1) In the past, using indirect Bi-Digital O-Ring Test, human or animal patients were diagnosed through an intermediate third person holding a good electrical conducting probe, the tip of which was touching the part of the patient to be examined. However, in order to diagnose the patient in isolation from a distance, or a dangerous or unmanagable unanesthesized animal, such as a lion or tiger, the author succeeded in making a diagnosis by replacing the metal conducting probe with a soft laser beam which is held by the one hand of the third person whose index finger is placed in close vicinity of the laser beam generated by a battery-powered penlight-type solid state laser generator. Thus, diagnosis within visible distance, without direct patient contact, became a reality. 2) Using a projection light microscope, by giving indirect Bi-Digital O-Ring Test while contacting with a fine electro-conductive probe on the magnified fine structure of normal and abnormal cells, various normal and abnormal intracellular substances were localized through a third person holding a pure reference control substance with the same hand that is holding the probe as an intermediary for the indirect Bi-Digital O-Ring Test. Instead of the photon beam in a light microscope, the author found that, using an electron beam passing through the close vicinity of specific molecules of specimens in an electron microscope, the molecular information is transmitted to the magnified fluorescent screen, and an indirect Bi-Digital O-Ring Test could be performed through a projected penlight-type solid state soft laser beam on the magnified intracellular structure through an observation glass window. Using the magnified fine structure of the cells, by either a light projection microscopic field or electron microscope, in various cancer cells of both humans and animals, Oncogen C-fos (AB2) and mercury were found inside of the nucleus. Integrin alpha 5 beta 1 was found on cell membranes and nuclear cell membranes of cancer cells. Acetylcholine was not found anywhere within cancer cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Identification of lysyl residues located at the substrate-binding site in UDP-glucose pyrophosphorylase from potato tuber: affinity labeling with uridine di- and triphosphopyridoxals.

Uridine di- and triphosphopyridoxals were used to probe the substrate-binding site in potato tuber UDP-glucose pyrophosphorylase (EC 2.7.7.9). The enzyme was rapidly inactivated in time- and dose-dependent manners when incubated with either reagent followed by reduction with sodium borohydride. The inactivations were almost completely retarded by UDP-Glc and UTP but only slightly by alpha-D-glucose 1-phosphate. The complete inactivation corresponded to the incorporation of about 0.9-1.0 mol of either reagent per mole of enzyme monomer. Both reagents appear to bind specifically to the UDP-Glc-(UTP)-binding site. Structural studies of the labeled enzymes revealed that the two reagents modified the identical set of five lysyl residues (Lys-263, Lys-329, Lys-367, Lys-409, and Lys-410), in which Lys-367 was most prominently modified. The ratios of the amounts of labels incorporated into these residues were similar for the two reagents. Furthermore, linear relationships were observed between the residual activities and the amounts of incorporation into each lysyl residue. We conclude that the five lysyl residues are located at or near the UDP-Glc(UTP)-binding site of potato tuber UDP-Glc pyrophosphorylase and that the modification of these residues occurs in a mutually exclusive manner, leading to the inactivation of the enzyme.

Affinity Labels↗