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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 55 records · Page 3Linked to original sources
PubMed2001

Blood transfusion causes deterioration in liver regeneration after partial hepatectomy in rats.

BACKGROUND: This study investigated the effects of blood transfusion on liver regeneration and function after hepatectomy in rats. METHODS: Inbred male Sprague-Dawley rats underwent a sham operation or a 70% hepatectomy (PHx) and were randomly divided into seven groups according to transfusion type: groups I and II underwent a sham operation and received saline (I) or whole blood (II). Groups III to VII underwent PHx with saline (III), whole blood (IV), irradiated/leukocyte-depleted whole blood (V), plasma (VI), or autologous blood (VII). The liver regeneration rate, proliferating cell nuclear antigen (PCNA) labeling index, serum aspartate aminotransferase, alanine aminotransferase, purine nucleoside phosphorylase (PNP) activity, hepatocyte growth factor (HGF), and activated transforming growth factor beta1 (TGF-beta(1)) were measured 6 and 24 h and 5 days after PHx. RESULTS: The liver regeneration rate and PCNA labeling index were lower in groups IV and V than in the other groups. Serum liver enzymes 6 h after PHx were worst in groups IV and V. PNP activity increased most in group IV, 6 and 24 h after PHx. The HGF values 6 h after PHx in all the transfused groups were lower than in group III. The activated TGF-beta(1) level 6 h after surgery was highest in group IV. CONCLUSION: Whole blood or irradiated/leukocyte-depleted whole blood impaired liver regeneration after PHx, probably through the production of activated TGF-beta(1) and HGF outside the liver, and plasma or autologous blood reduced the deleterious effects.

Animals↗
PubMed2001

Effect of parathyroid hormone on cortical bone response to in vivo external loading of the rat tibia.

Cortical bone responses following administration of parathyroid hormone (PTH) were evaluated using a four-point bending device to clarify the relationship between the effect of PTH and mechanical loading. Female Wistar rats, 6-months-old, [corrected] were used. Rats were randomized into three groups (n = 10/group), namely PTH-5 (5 microgram PTH/kg body weight), PTH-30 (30 microgram PTH/kg body weight), and PTH-v (vehicle). PTH (human PTH (1-34)) was injected subcutaneously three times/week for 3 weeks. Loads on the right tibia were applied in vivo at 29.1 +/- 0.3 N for 36 cycles at 2 Hz 3 days/week for 3 weeks using four-point bending. The administration of PTH and tibial mechanical loading were performed on the same day. After calcein double labeling, rats were killed and tibial cross-sections were prepared from the region with maximal bending at the central diaphysis. Histomorphometry was performed over the entire periosteal and endocortical surfaces of the tibiae, dividing the periosteum into lateral and medial surfaces. The in vivo average peak tibial strains (predicted) on the lateral periosteal surface were 1392.4, 1421.8 and 1384.7 (mu)strain in PTH-v, PTH-5 and PTH-30 groups, respectively, showing no significant difference among the three groups. Significant loading-related increases in the bone formation surface, mineral apposition rate, and bone formation rate were observed at the periosteal and endocortical surfaces. Significant differences between PTH groups were also seen. Interaction between mechanical loading and PTH was significant at both periosteal and endocortical surfaces. It is concluded that PTH has a synergistic effect on the cortical bone response to mechanical loading.

Animals↗
PubMed2001

A three-dimensional, quantitative computed tomographic study of changes in distribution of bone mineralization in the developing human mandible.

The three-dimensional distribution of highly mineralized cortical bone on the buccal surface of the mandible was evaluated using quantitative computed tomography. The study was completed in 34 living persons (21 females and 13 males) between the ages of 9 and 32 yr of age with symmetrical mandibles. The geometrical distribution of the highly mineralized areas (>1250 mg/cm(3)) was determined by three-dimensional reconstruction of images. The pattern of distribution was evaluated by superimposing a 9 by 9-mesh grid over the lateral view of the mandible and adapting it to the same anatomical landmarks for different aged participants. Individuals demonstrated four different patterns of distribution of highly mineralized buccal cortical bone. The youngest had highly mineralized bone in the corpus of the mandible and along the anterior ramal border. In older individuals, the mineralization changed to include the mid- and posterior ramus. Highly mineralized bone was not found within the condylar, coronoid, or gonial angle regions of any participant. A comparison of the mineralization pattern between the left and right lateral mandibular views showed bilateral symmetry with similar patterns of distribution. Comparison of the number of grids occupied by highly mineralized cortical bone with the age of the participant, mandibular length, gonial angle, and cross-sectional area of the masseter muscle produced the highest correlation coefficient with the size of the masseter muscle.

Adolescent↗
PubMed2001

Intact microglia are cultured and non-invasively harvested without pathological activation using a novel cultured cell recovery method.

Because spontaneous host regeneration of damaged tissues is limited, novel therapeutics utilizing cultured cells with the aid of tissue engineering methods are promising alternatives for tissue replacement. One critical shortcoming is current requirement for invasive cell harvest from culture to fabricate cell-based devices. Although microglia that secrete neurotrophic factors are attractive candidates for novel cell transplantation therapy for damaged central nervous system tissue, the intact harvest of cultured microglia is presently not achievable. Therefore, primary microglia were plated onto culture surfaces grafted with the temperature-responsive polymer, poly(N-isopropylacrylamide) (PIPAAm). This surface undergoes rapid, reversible temperature-dependent changes in its hydration state and surface hydrophilicity. Microglia attached and proliferated on PIPAAm-grafted dishes at 37 degrees C. By reducing culture temperature, more than 90% of the cells spontaneously detached from the dishes within several minutes without trypsin or EDTA treatment. Recovered and replated microglia exhibited phenotypic properties comparable to those of primary microglia freshly isolated from brain. By contrast, less than 60% of the cells were harvested by trypsin digestion, and exhibited significant alteration of characteristic cellular properties as monitored by pathological states in vivo. This new technology exhibits utility for the preparation of cell sources required for cell transplantation as well as microglial function analysis.

Animals↗
PubMed2001

Synthesis and evaluation of A-ring diastereomers of 1alpha,25-dihydroxy-22-oxavitamin D3 (OCT).

A-ring diastereomers of 1alpha,25-dihydroxy-22-oxavitamin D3 (OCT) (2), 3-epi-1alpha,25-dihydroxy-22-oxavitamin D3 (3-epiOCT) (3) and 1,3-diepi-1alpha,25-dihydroxy-22-oxavitamin D3 (1,3-diepiOCT) (4) were synthesized by the convergent method. In vitro binding affinity for rat vitamin D binding protein and calf-thymus vitamin D receptor, differentiation-inducing activity on HL-60 cells, and transcriptional activity of 3-epiOCT (3) and 1,3-diepiOCT (4) were evaluated in comparison with OCT (2), 1-epi-1alpha,25-dihydroxy-22-oxavitamin D3 (1-epiOCT) (5) and 1alpha,25-dihydroxyvitamin D3 (1).

Animals↗
PubMed2001

Highly potent cell differentiation-inducing analogues of 1alpha,25-dihydroxyvitamin D3: synthesis and biological activity of 2-methyl-1,25-dihydroxyvitamin D3 with side-chain modifications.

Eight 2-methyl substituted analogues of 20-epi-22R-methyl-1alpha,25-dihydroxyvitamin D3 (5) and 20-epi-24,26,27-trihomo-22-oxa-1alpha,25-dihydroxyvitamin D3 (6: KH-1060) were convergently synthesized. Preparation of the CD-ring portions with modified side chains of 5 and 6, followed by palladium-catalyzed cross-coupling with the A-ring enyne synthons (20a-d), (3S,4S,5R)-, (3S,4R,5R)-, (3S,4S,5S)- and (3R,4R,5S)-3,5-bis[(tert-butyldimethylsilyl)oxy]-4-methyloct-1-en-7-yne, afforded two sets of four A-ring stereoisomers of 20-epi-2,22-dimethyl-1,25-dihydroxyvitamin D3 (7a-d) and 20-epi-24,26,27-trihomo-2-methyl-22-oxa-1,25-dihydroxyvitamin D3 (8a-d). The biological profiles of the hybrid analogues were assessed in terms of affinity for vitamin D receptor (VDR) and HL-60 cell differentiation-inducing activity in comparison with the natural hormone. The combined modifications of the A-ring at the 2-position and the side chain yielded analogues with high potency.

Antineoplastic Agents↗
PubMed2001

Synthesis and biological evaluation of all A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) and their 20-epimers: possible binding modes of potent A-ring analogues to vitamin D receptor.

BACKGROUND: The secosteroid 1 alpha,25-dihydroxyvitamin D(3) (1) has a wide variety of biological activities, which makes it a promising therapeutic agent for the treatment of cancer, psoriasis and osteoporosis. Insight into the structure-activity relationships of the A-ring of 1 is still needed to assist the development of more potent and selective analogues as candidate chemotherapeutic agents, as well as to define the molecular mode of action. RESULTS: All possible A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) (6a-h) and their 20-epimers (7a-h) were designed and efficiently synthesized. The dependence of the affinities for vitamin D receptor (VDR) and vitamin D binding protein (DBP), as well as the HL-60 cell differentiation-inducing activity, upon the stereochemistry of the A-ring and at C20 in the side chain was evaluated. CONCLUSIONS: The binding affinities and potency of the 5,6-trans and 5,6-cis analogues were enhanced by a 2-methyl substituent in a certain orientation. Molecular docking studies based upon the X-ray crystal structure of VDR suggested that the axial 2-methyl group would be accommodated in a pocket surrounded by hydrophobic amino acid residues in the ligand binding domain, resulting in enhanced interaction.

Animals↗
PubMed2001

Bone mass changes of tibial and vertebral bones in young and adult rats with collagen-induced arthritis.

To study the effect of arthritis on bone mass, bone mineral density (BMD) of cancellous and cortical bone in the tibial metaphysis and diaphysis in 2- and 7-month-old rats with collagen-induced arthritis (CIA) was serially measured using peripheral quantitative computed tomography (pQCT). BMD in the fourth lumbar vertebra in 7-month-old CIA rats was also measured by pQCT. The fourth lumbar vertebral body, distal femur, and proximal tibia in 7-month-old CIA rats were analyzed histomorphometrically. Changes in BMD differed between 2-month-old (young) and 7-month-old (adult) CIA rats. Although the BMD for the proximal tibia (2 mm and 5 mm distal from the growth cartilage) in young CIA rats decreased compared with that in control rats, the values exceeded the initial value during the arthritis course. On the other hand, bone loss in adult CIA rats occurred predominantly in the cancellous bone of the periarticular region of the tibia (2 mm distal from the growth cartilage), in which the enhancement of bone resorption and reduced bone formation were observed histomorphometrically. No remarkable changes were demonstrated in BMD or histomorphometrical analysis for the lumbar vertebra during the experimental course. These results suggest that bone loss in adult CIA rats resembles the osteoporosis that develops during the early stage of human rheumatoid arthritis. We conclude that adult CIA rats are more appropriate than young CIA rats as an experimental model of secondary osteoporosis due to rheumatoid arthritis.

Age Factors↗
PubMed2001

Effects of ovariectomy and estrogen replacement therapy on arthritis and bone mineral density in rats with collagen-induced arthritis.

We investigated the effects of ovariectomy (ovx) and estrogen replacement therapy (ERT) on bone mineral density (BMD) and arthritis severity in rats with collagen-induced arthritis (CIA). Seven-month-old female Sprague-Dawley rats were separated into a sham group (n = 8), CIA group (n = 14), ovx group (n = 10), CIA + ovx group (n = 11), and CIA + ovx + ERT group (n = 14). In these groups, ovx was performed at 7 days, and ERT (17beta-estradiol at 20 microg/kg three times per week) was initiated 8 days after sensitization. Every 2 weeks, until 8 weeks after sensitization, arthritis score and hind paw thickness were evaluated, and BMD of the trabecular and cortical bones in the metaphysis and diaphysis of the tibia were measured by peripheral quantitative computed tomography. The arthritis score was highest in the CIA + ovx group at all timepoints after sensitization. The hind paw thickness was significantly higher in the CIA + ovx group than in the CIA group at 8 weeks after sensitization (p < 0.05). Both the arthritis score and hind paw thickness were lower in the CIA + ovx + ERT group than in the CIA + ovx group. BMD in the metaphysis was significantly decreased in both the trabecular and cortical bones in the CIA + ovx group compared with those in the CIA group at 4, 6, and 8 weeks after sensitization. In the CIA + ovx group, trabecular BMD was changed by -34 +/- 11%, and cortical BMD changed by -14 +/- 7% in the metaphysis at 8 weeks compared with those at 0 week. In the CIA group, changes of BMD in the metaphysis were -7 +/- 11% in trabecular bone and 0 +/- 7% in cortical bone. These differences of trabecular and cortical bone loss in the metaphysis were significant (both p < 0.01). BMD reduction was significantly less in the CIA + ovx + ERT group than in the CIA + ovx group at 6 and 8 weeks after sensitization. Although BMD in the diaphysis was also reduced in the groups with CIA, the degree of reduction was smaller than in the metaphysis. We conclude that ovx in CIA rats could enhance the severity of arthritis and bone loss, and that ERT could suppress arthritis and bone loss.

Animals↗
PubMed2001

Efficiency of rice bran for removal of organochlorine compounds and benzene from industrial wastewater.

Rice bran was found to effectively adsorb several organic compounds, such as dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and benzene. Equilibrium adsorption isotherms conformed to the Freundlich type (log-log linear). The adsorption of dichloromethane and chloroform by rice bran was observed over the range of pH 1-11. Therefore, rice bran is applicable for treatment of wastewater over a wide pH range. Dichloromethane was successfully removed from water samples with an average removal efficiency of 70% after 60 min when rice bran was added to water samples containing from 0.006 to 100 mg/L dichloromethane. The removal of these organochlorine compounds and benzene by rice bran was attributed to the uptake by intracellular particles called spherosomes. Here, we report the results of a fundamental study of the efficiency of rice bran for removal of organochlorine compounds and benzene using a batch system on the laboratory scale, and describe elucidation of the mechanism of removal of these compounds by rice bran.

Adsorption↗
PubMed2001

Chicken pineal clock genes: implication of BMAL2 as a bidirectional regulator in circadian clock oscillation.

BACKGROUND: In a transcription/translation-based autoregulatory feedback loop of vertebrate circadian clock systems, a BMAL1-CLOCK heterodimer is a positive regulator for the transcription of the negative element gene Per. The chicken pineal gland represents a photosensitive clock tissue, but the pineal clock genes constituting the oscillator loop have been less well characterized. RESULTS: We identified expression of the Per2, Bmal1, Bmal2 and Clock genes in the chicken pineal gland. Messenger RNA levels of these genes exhibited overt circadian rhythms in the pineal cells, both in vivo and in culture. In vitro functional analyses revealed the formation of cBMAL1-cCLOCK and cBMAL2-cCLOCK heteromers. Both of the cBMAL-cCLOCK heteromers activated E-box element-dependent transcription, which was negatively regulated by cPER2 in luciferase assays. Co-expression of cCLOCK, cBMAL1 and cBMAL2 co-operatively activated E-box element-dependent transcription, and a greater level of expression of cBMAL2 inhibited the activation. In the cultured pineal cells, an over-expression of either cBMAL1 or cBMAL2 disrupted the circadian rhythm of melatonin production. CONCLUSION: The functional characterization of the chicken pineal clock molecules supports the key roles of BMAL1, BMAL2 and CLOCK which contribute to the E-box-dependent transcriptional regulation in the circadian clock system.

ARNTL Transcription Factors↗
PubMed2001

A clinical and histological evaluation of titanium mini-implants as anchors for orthodontic intrusion in the beagle dog.

The aim of this study was to determine the anchorage potential of the titanium mini-implant for orthodontic intrusion of the mandibular posterior teeth. Six mini-implants were surgically placed around the mandibular third premolars on each side in 3 adult male beagle dogs. On the buccal site, three mini-implants were placed distal to the apex of the distal root of the third premolar, at the interradicular septa of the third premolar, and mesial to the apex of the mesial root of the third premolar, as linearly as possible. The same procedure was performed at the lingual site on both sides of the mandibular third premolars in each dog. Bilateral interradicular mini-implants on both the buccal and the lingual sites were used as the anchorage for the intrusion of the third premolars (loaded implants) and the other mini-implants were used as control (unloaded) implants. In 6 weeks, an intrusive force (150 g) was applied between the interradicular implants on the buccal and the lingual sites by closed coil springs run across the crowns of the third premolars. After 12 to 18 weeks of orthodontic intrusion, the animals were killed and their mandibles were dissected and prepared for histologic and fluorescent observation. The results indicated that the mandibular third premolars intruded 4.5 mm, on average, after 12 to 18 weeks of orthodontic force application, with mild root resorption at the furcation area as well as the root apex. All the mini-implants remained stable during orthodontic tooth movement without any mobility or displacement. The morphometrical findings indicated that the calcification of the peri-implant bone on the loaded implants was equal to or slightly greater than those of the controls. In addition, 6 of the 36 mini-implants were removed after tooth movement, and all of them were easily removed with a screwdriver. These findings suggest that mini-implants are effective tools for the anchorage of orthodontic intrusion in beagle dogs.

Alveolar Process↗
PubMed2001

Two-dimensional manipulation of cardiac myocyte sheets utilizing temperature-responsive culture dishes augments the pulsatile amplitude.

Although cardiac myocytes adherent to tissue culture polystyrene (TCPS) dishes retain the spontaneous beating, the pulsatile amplitude is highly limited compared to that in vivo. One of the main reasons for the limited pulsation may be the interface between the cells and the TCPS surfaces. Release of these cells from rigid TCPS surfaces may augment their pulsatile amplitude. With this perspective, we have developed a novel cell manipulation technique to detach cultured cardiac myocytes from rigid surfaces and to rescue higher pulsatile amplitude of the cells using temperature-responsive culture dishes and discuss the possibility of improving this heart tissue model. Primary cardiac myocytes were cultured on the slightly hydrophobic dish surfaces grafted with a temperature-responsive polymer, poly(N-isopropylacrylamide). Cells adhered and proliferated, forming confluent cardiac myocyte sheets in a fashion similar to those on ungrafted TCPS dishes. Decrease in culture temperature resulted in surface change of the polymer from slight hydrophobic to highly hydrophilic due to extensive hydration of the grafted polymer on the dishes. This results in release of cardiac myocyte sheets from the dishes without enzymatic or EDTA treatment. When no support was used, the detached cardiac myocyte sheets shrank to one-tenth size, which ceased their pulsation. When chitin membranes were used to support the confluent sheets to prevent cell shrinkage, the detached cell sheets could be transferred and readily adhered onto another virgin TCPS dishes. These transferred cell sheets preserved the similar cell morphology and pulsation to those before the detachment. When polyethylene meshes were used to support cell sheet transfer, detached cardiac myocyte sheets partially attached to the mesh threads. Then, the constructs were inverted and placed in another culture dish to prevent direct association to dish surfaces. Moreover, the cardiac myocyte sheets were reorganized to heart tissue-like structures by the unisotropic contraction orientated by the mesh threads, and the pulsatile amplitude increased more than 10 times higher. This technique would bring about new insight in tissue engineering as well as cultured heart model.

Animals↗
PubMed2001

Thermo-responsive culture dishes allow the intact harvest of multilayered keratinocyte sheets without dispase by reducing temperature.

To develop new technology for harvesting transplantable cultured epithelium without dispase treatment, human keratinocytes were plated on culture dishes grafted with a thermo-responsive polymer, poly(N-isopropylacrylamide). The grafted dish surfaces are slightly hydrophobic above 32 degrees C, but reversibly change to hydrophilic below this temperature. According to the method of Rheinwald and Green, keratinocytes proliferated and made a multilayer on the grafted surfaces at 37 degrees C, as on the nongrafted culture dishes. The multilayered keratinocyte sheets were detached from the grafted surfaces only by reducing temperature to 20 degrees C without need for dispase. No cell remnants were observed on the dishes. Such cell sheet detachment was not observed on nongrafted dishes. Immunoblotting of harvested keratinocyte sheets revealed that dispase treatment disrupted E-cadherin and laminin 5, while these molecules remained intact in the keratinocyte sheets harvested by only reducing temperature from the grafted dishes. Transmission electron microscopy revealed that desmosomes were destroyed in dispase treatment but retained in low-temperature treatment. Use of thermo-responsive dishes was examined as a new tool for tissue engineering to achieve the preparation of artificial epithelium for cell transplantation as well as for the investigation of intact multilayered keratinocyte sheets.

Cell Culture Techniques↗
PubMed2001

Cortical bone mineral density in asymmetrical mandibles: a three-dimensional quantitative computed tomography study.

The three-dimensional distribution (3D) of the highest mineralized cortical bone was evaluated in 32 subjects between the ages of 8 and 30 years with asymmetrical mandibles using quantitative computed tomography (QCT). The geometrical distribution of the highest mineralized areas (> 1250 mg/cm3) representative of mandibular cortical bone was determined by 3D reconstruction of the images. The length of the mandible on each side was determined by defining a new linear measurement from the centre of the 3D reconstructed condyle to the midline of the symphysis as identified from a submental view. The cross-sectional areas of the masseter and medial pterygoid muscles were assessed from bilateral axial views through the middle of the muscles parallel to the Frankfort-Horizontal plane. Comparison between the lengths of the two mandibular sides (right-left = mm) indicated a range of asymmetries with an equal number of subjects with the left and right mandible longer. Comparison of the area of highest mineralized cortical bone between the right and left sides (R/L) to the ratio of the mandibular length (R/L) showed a high correlation coefficient (r = 0.629) suggesting that the shortest mandibular side had more highly mineralized bone. A comparison of the area of highest mineralized cortical bone between the right and left sides (R/L) to the ratio of cross-sectional areas of the muscles showed the highest correlation coefficient (r = 0.724) with the ipsilateral masseter muscle. These findings indicate that asymmetrical mandibles are associated with asymmetrical distributions of the highest mineralized cortical bone and that this is age dependent.

Adolescent↗
PubMed2001

Effect of brefeldin A on melatonin secretion of chick pineal cells.

Melatonin is secreted from the pineal gland in a circadian manner. It is well established that the synthesis of melatonin shows a diurnal rhythm reflecting a daily change in serotonin N-acetyltransferase (NAT) activity, and the overall secretion of melatonin requires a cellular release process, which is poorly understood. To investigate the possible involvement of Golgi-derived vesicles in the release, we examined the effect of brefeldin A (BFA), a reversible inhibitor of Golgi-mediated secretion, on melatonin secretion of cultured chick pineal cells. We show here that treatment with BFA completely disassembles the Golgi apparatus and reduces melatonin secretion. In more detailed time course experiments, however, the inhibition of melatonin secretion is only observed after the removal of BFA in parallel with the reassembly of the Golgi apparatus. This inhibition of melatonin secretion is not accompanied by accumulation of melatonin in the cells. These observations indicate that chick pineal melatonin is released independently of the Golgi-derived vesicles, and suggest inhibition of melatonin synthesis after the removal of BFA. By measuring the activities and mRNA levels of melatonin-synthesizing enzymes, we found that the removal of BFA specifically inhibits NAT activity at the protein level. On the other hand, BFA causes no detectable phase-shift of the chick pineal oscillator regulating the circadian rhythm of melatonin secretion. The results presented here suggest that the Golgi-mediated vesicular transport is involved in neither the melatonin release nor the time-keeping mechanism of the circadian oscillator, but rather contributes to the regulation of NAT activity.

Animals↗
PubMed2001

Regulatory mechanism for the stability of the meta II intermediate of pinopsin.

Pinopsin is a chicken pineal photoreceptive molecule with a possible role in photoentrainment of the circadian clock. Sequence comparison among members of the rhodopsin family has suggested that pinopsin might have properties more similar to cone visual pigments than to rhodopsin, but the lifetime of the physiologically active intermediate (meta II) of pinopsin is rather similar to that of metarhodopsin II, which is far more stable than meta II intermediates of cone visual pigments [Nakamura, A. et al., (1999) Biochemistry 38, 14738-14745]. In the present study, we investigated the amino acid residue(s) contributing to this unique property of pinopsin by using site-directed mutagenesis to pinopsin-specific structural features, (i) Ser171, (ii) Asn184, and (iii) the second extracellular loop two-amino acids shorter than that of cone visual pigments. The meta II stability of the 171/184 double mutant of pinopsin (S171R/N184D) is almost the same as that of wild-type pinopsin. In contrast, the meta II lifetime is markedly shortened (one third) by introduction of the third mutation (replacement of a six-amino acid stretch, 188-193, by the corresponding eight residues of chicken green-sensitive cone pigment) to the 171/184 double mutant of pinopsin. Consistently, meta II of the green-sensitive pigment mutant, in which the eight-amino acid stretch is inversely replaced by the corresponding six residues of pinopsin, is more stable than meta II of the wild-type pigment. These results strongly suggest that the specific sequence and/or the number of residues at amino acids 188-193 in pinopsin play an important role in the stabilization of the meta II intermediate.

Amino Acid Substitution↗