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Conformational changes in blood serum albumin under heart ischemia are found from the dispersion parameters of optical rotation and circular dichroism. It is also found that patients with myocardium infarction have a considerable amount of carbohydrate components in the modified albumin form.
A cerebrospinal fluid (CSF) glucose biosensor is introduced. The biosensor is a polarimeter that measures the rotation of plane polarized light proportional to glucose concentration. Preliminary in vitro studies revealed a linear response with good sensitivity over a range of glucose solutions (0-400 mg/dl). Anesthetized, adult dogs underwent intravenous glucose loading, and these preliminary in vivo studies resulted in good correlation (r = 0.98) between CSF polarimeter readings and CSF glucose by laboratory assay. This in vivo correlation suggests that both mutarotation of glucose anomer and changes from other optically active substances present in CSF are either negligible or constant over the range of glucose concentrations studied. The CSF polarimeter showed a significant rise soon after the intravenous loading of glucose (1-30 min) but a longer lag time (45-60 min) between the peak blood glucose and peak CSF polarimeter reading. This preliminary work extends, to the CSF, the concept of measuring optical rotation.
One mechanism previously proposed for the abiotic accumulation of molecules of one chirality in nature is asymmetric adsorption on the chiral surfaces of optically active quartz crystals. Earlier literature in this field is reviewed, with the conclusion that previous investigations of this phenomenon, using optical rotation criteria, have afforded ambiguous results. We now have studied the adsorption of radioactive D- and L-alanine on powdered d- and l-quartz, using change in radioactivity level as a criterion for both gross and differential adsorption. d-Quartz preferentially adsorbed D-alanine from anhydrous dimethyl-formamide solution, and l-quartz L-alanine. The differential adsorption varied between 1.0 and 1.8%. The implications of these observations are discussed from the viewpoint of early chemical evolution and the origin of optically active organic compounds in nature.
Uricase (urate:oxygen oxidoreductase, EC 1.7.3.3) exposes a positional and steric specificity in the enzymic conversion of urate to allantoin. C-2 of urate was recovered as C-2 of allantoin. By the consecutive oxidation and hydrolysis reactions a levorotatory intermediate was formed, presumably (-)-2-oxo-4-hydroxy-4-carbohydroxy-5-ureido-imidazoline. The absorption and optical rotation dispersion spectra of the intermediate were established. In the presence of borate buffer, the intermediate was transformed to (+)-alloxanate. The decay of the former compound depends on general base and acid catalysis. RS-(+/-)-allantoin was formed by chemical decarboxylation and S-(+)-allantoin by enzymic decarboxylation.
The authors studied the optic rotation dispersion of serum albumin in patients suffering from cholecystitis and acute appendicitis. Conforming changes in these forms of pathology characterized by despiralization processes were established. A method of purification of albumin from its modified forms, possibly causing the mentioned changes in the albumin structure is suggested.
OBJECTIVE: To record the prevalence and document the types of eye disease in population of Thoroughbred racehorses in Victoria, Australia. DESIGN: Prospective study. ANIMALS: Two hundred four Thoroughbred racehorses. PROCEDURE: All horses and both eyes were examined at four metropolitan and two country racing stable complexes. Ophthalmic exam was performed following dark adaptation with a transilluminator, biomicroscope, and direct ophthalmoscope. Intraocular pressures were measured when indicated. Both pupils were dilated with tropicamide when indicated. RESULTS: One hundred eighty-two (89.2%) flat-racing and 22 (10.8%) jump-racing (hurdle or steeple) horses were examined. Age range: 2-9 years (mean 3.7 years, median 3); 97 (47.5%) male-neuter, 74 (36. 3%) female, 33 (16.2%) male. Potential vision-threatening eye disease was present in 15 (7.4%) different horses: complete lenticular cataracts 3, posterior lens luxation and cataract 1, large peripapillary 'butterfly' inactive lesions 3, large peripapillary 'butterfly' active lesions 2, peripapillary focal inactive 'bullet hole' chorioretinal lesions (> 20) 5, optic nerve atrophy 1. Non-vision threatening eye disease was present in 117 (57.4%) different horses, involving one or more ocular structures: lower eyelid scars 3; periocular fibropapillomatous disease 1; third eyelid squamous cell carcinoma 1; corneal scars 6; corneal band opacity 2; anterior iris synechia 1; developmental cataracts 36 (17.2%); peripapillary focal inactive 'bullet hole' chorioretinal lesions (< 20) 103 (50.0%); linear peripapillary hyperpigmentation bands 16 (7.9%). Unusual variations of normal ocular anatomy and colobomata was recorded in 11 (5.4%) different horses: granular iridica hypoplasia 3, granular iridica hyperplasia 2, multilobular granular iridica cyst 1, microcornea 1, hyaloid remnant 1, rotated optic nerve head 1, coloboma of the lens 1, atypical coloboma of the retina 1. CONCLUSIONS: This survey demonstrates that the prevalence of vision-threatening eye disease in racing horses may be greater than previously perceived, and highlights the importance of ocular examination within any routine physical examination of horses.
Complex spike activity of floccular Purkinje cells responds to patterns of rotational optic flow about the vertical axis (rVA neurons) or a horizontal axis 45 degrees to the midline (rH45 neurons). The pigeon flocculus is organized into four parasagittal zones: two rVA zones (zones 0 and 2) interdigitated with two rH45 zones (zones 1 and 3). Climbing fiber input to the rVA and rH45 zones arises in the caudal and rostral regions of the medial column of the inferior olive (mcIO), respectively. To determine whether the two rVA zones and the two rH45 zones receive input from different areas of the caudal and rostral mcIO and whether individual neurons project to both zones of the same rotational preference, different colors of fluorescent retrograde tracer were injected into the two rVA or two rH45 zones. For the rVA injections, retrogradely labeled cells from the two zones were intermingled in the caudal mcIO, but the distribution of cells labeled from zone 0 was slightly caudal to that from zone 2. On average, 18% of neurons were double labeled. For the rH45 injections, cells retrogradely labeled from the two zones were intermingled in the rostral mcIO, but the distribution of cells labeled from zone 1 was slightly rostral to that from zone 3. On average, 22% of neurons were double labeled. In sum, each of the two rVA zones and the two rH45 zones receives input from slightly different regions of the mcIO, and about 20% of the neurons project to both zones.
Optically active 1- or 3-acyl-sn-glycerols were synthesized from 2,3- or 1,2-isopropylidene-sn-glycerols, respectively. The 2,3- or 1,2-isopropylidene-sn-glycerols were condensed with appropriate long saturated or unsaturated fatty acids and the resulting acyl isopropylidene compounds were treated with dimethylboronbromide at - 50 degrees C to give the title compounds. The ketal cleavage of acyl isopropylidene-sn-glycerols by dimethylboronbromide to produce the long 1- or 3-acyl-sn-glycerols was effective and gave good yields (70-90%). The reaction conditions were mild and there was no acyl migration, as shown by optical rotation of the monoacyl-sn-glycerols. The synthesis of 2,3-isopropylidene-sn-glycerol was improved to give an overall yield of 40% from L-arabinose. L-Arabinose was first converted to its 1,1'-diethylmercapto derivative and then condensed with 2-methoxypropene to yield 1,1'-diethyl-mercapto-4,5-isopropylidene-L-arabinose. Oxidation of this compound with sodium periodate followed by reduction with sodium borohydride under alkaline conditions yielded 2,3-isopropylidene-sn-glycerol [alpha]22D = -14.90 degrees, neat (Lit. 8 [alpha]22D = -14.5 degrees, neat; 14 [alpha]25D = -10.8 degrees; methanol C, 16.9). The optical purity of isopropylidene-sn-glycerols was determined as benzoyl derivatives on a high performance liquid chromatographic column packed with a chiral stationary phase.
The position and orientation of the thorax and head of flying blowflies (Calliphora vicina) were measured using small sensor coils mounted on the thorax and head. During flight, roll movements of the thorax are compensated by counter rolls of the head relative to the thorax. The yaw turns of the thorax (thorax saccades) are accompanied by faster saccades of the head, starting later and finishing earlier than the thorax saccades. Blowfly flight can be divided into two sets of episodes: 'during saccades', when high angular velocities of up to a few thousand degrees per second are reached by both the thorax and head, and 'between saccades', when the orientation of the thorax and, in particular, the head is well stabilized. Between saccades, the angular velocities of the head are approximately half those of the thorax and lie mostly in the range 0-100 degrees s-1 for any rotation (yaw, pitch and roll). These velocities are low enough to limit the visual blur attributable to rotation. It is argued that the split into periods during which either rotational optic flow ('during saccades') or translatory optic flow ('between saccades') dominates is helpful for processing optic flow when signals and neurons are noisy.
beta-Hydroxydiaminopimelic acid, together with some diaminopimelic acid, occurs in the cell-wall mucopeptide of certain Actinomycetales. These components were converted into their di-DNP derivatives and separated by chromatography. Hence the relative proportions present in the cell walls of a number of species were measured. The problem of acid-induced inversion of configuration was studied. Of the diaminohydroxypimelic acids isomer B (see Scheme 2; amino groups meso, hydroxy group threo to its neighbouring amino group) always predominated but a small proportion of isomer D (amino groups l, hydroxy group erythro) also occurred. The configuration of the diaminohydroxypimelic acids was determined by periodate oxidation to glutamic gamma-semialdehyde, which underwent spontaneous ring-closure. Reduction with sodium borohydride produced optically active proline, the configuration of which was determined by direct measurement of the optical rotation of DNP-proline. Un-cross-linked diaminohydroxypimelic acid in the cell wall was oxidized with periodate in the presence of ammonia. Since the remaining amino group was bound in peptide linkage, ring-closure was prevented and borohydride reduction of the aldehyde-ammonia presumed to be present resulted in the formation of ornithine. The quantity of ornithine was used as a measure of the degree of cross-linking.
The frequency and causes of diagnostic errors are discussed on the basis of 2,099 case histories of ovarian and uterine tumors. The use of physico-chemical characteristics of serum albumin as an additional means of diagnosis of these diseases in 16 patients and 20 healthy subjects was studied. Patients revealed changes in dispersion of optical rotation of serum albumin which suggest its despiralization. Although being nonspecific, changes in the extent of despiralization vary depending on tumor advancement and gravity of patient's condition. The level of modified serum albumin is also in correlation with tumor process and the patient's state, the highest values being registered at later stages of the disease.
The effect of gel-sol transition in kappa-carrageenan systems on the microviscosity of hydrophobic microdomains, as well as its relation to macroscopic rheology and molecular conformation, was studied in kappa-carrageenan systems. The microdomains were probed by 1,3-di(-1-pyrenyl)propane (P3P) for which the excimer intensity (Ie) provides relative measures of the microviscosity in the immediate probe surroundings. In particular the applicability of P3P to monitor the gel--sol transition was proved, the results showing a dramatic decrease in microviscosity in the vicinity of the transition point. The corresponding changes in rheological properties and carrageenan conformation were investigated by dynamic viscometry (DV) and optical rotation (OR), respectively. The temperature of onset of the transition as indicated by the microviscosity data (T0) was found to correlate well with the OR and DV-results. The application of microviscosity and OR-measurements allowed an estimation of the helical content at T0 to be determined. P3P-data indicate a microenvironment viscosity for the probe sites in the kappa-carrageenan system comparable to that found in SDS micelles.
Viscosity, dispersion of optical rotation and circular dichroism of collagen solutions was determined. Collagen solutions were obtained after treating collagen with enzymes--protorizine or prototerrizine, or with the mixture of 2,5 M NaOH--1 M Na2SO4 and acid-soluble collagen from calf skin. Molecules of "forcedly" solved collagen have an asymmetric shape with a conformation of a three-helical helix. After being heated the latter undergoes the transformation helix-coil similar to tropocollagen molecules.
1. The effect of removing Mg(2+) from a purified high-molecular-weight (1.07x10(6)) fraction of Escherichia coli ribosomal RNA was examined by ultracentrifugation, thermal denaturation and optical rotation. 2. At moderate I (0.1m-sodium chloride), EDTA at 2-50mm has little effect on RNA; at low I, 0.01-0.04 (with tris as counter-ion), two boundaries appear. 3. The leading boundary, S(20,w) about 20s, is identified with the original material with counter-ion Mg(2+) (;ionic atmosphere') removed, leading to an expanded form. 4. The slow boundary, 15-16s, is associated with a further loss of Mg(2+) and a further expansion, sensitive to EDTA concentration: it is proposed that this Mg(2+) is localized on the polynucleotide chain, i.e. ;site-bound'. 5. I is important and the EDTA effect at low I is reversible if Na(+) is added immediately after the EDTA: this Na(+) reversibility is lost on standing at 0 degrees . It is suggested that changes in the tertiary structure may be associated with this loss of reversibility. 6. Thermal-denaturation studies show that there is no loss of secondary structure associated with these changes: change in the optical-rotatory-dispersion spectrum in the region of the Cotton effect may be associated with this change in tertiary structure.
The fungus Aspergillus ficuum NRRL 3135 is known to produce an extracellular nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with a pH optimum of 2.0, as well as an extracellular myo-inositol hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with pH optima of 2.0 and 5.5. Both these enzymes are also known to hydrolyze myo-inositol hexaphosphate. The pentaphosphates liberated in the first step of this hydrolysis have been isolated and identified by ion-exchange chromatography and optical rotation. The nonspecific orthophosphoric monoester phosphohydrolase produces a single pentaphosphate, d-myo-inositol-1,2,4,5,6-pentaphosphate, whereas the phytase, at both pH 2.0 and 5.5, produces a mixture of two pentaphosphates. The major component of this mixture is d-myo-inositol-1,2,4,5,6-pentaphosphate and the other is d-myo-inositol-1,2,3,4,5-pentaphosphate. Thus the pathways of dephosphorylation of myo-inositol hexaphosphate by these two enzymes differ from that of wheat-bran phytase which forms l-myo-inositol-1,2,3,4,5-pentaphosphate.
The behavior and properties of ovine prolactin have been evaluated by measurements of fluorescence, polarization of fluorescence, absorption, optical rotation, and circular dichroism. The helical content of the native molecule at pH 8 is 60 per cent as determined by circular dichroism. Three molecular transitions have been followed. The one in acid affects only 20 per cent of the helical residues. More profound conformational changes occur in urea solutions (pH 5.2 and 8.0) where most of the helical residues are randomized. There is a close parallel between the behavior of ovine prolactin and bovine growth hormone both in aqueous solutions between pH 2 and 11.5 and in urea solutions at pH 5.2 and 8.0. Based on the similarities in behavior it is proposed that the conformations of these two hormones are homologous.
Products, substrates, and inhibitors of the threonine dehydratase from sheep liver (EC 4.2.1.16) have been investigated by proton nuclear magnetic resonance and optical rotation. The alpha-ketobutyrates produced from L-threonine and L-allothreonine in 2H2O have been shown to incorporate a single deuterium into the beta position. The dehydratase forms R-alpha-ketobutyrate-beta-d from L-threonine and L-allothreonine. The alpha protons of the substrates, threonine and allothreonine, do not exchange in the presence of the dehydratase. In the presence of dehydratase, the competitive inhibitors L-cysteine and L-alanine undergo alpha-proton exchange. Highly purified dehydratase has been used to determine kinetic parameters for the usbstrates L-threonine, L-allothreonine, L-serine, and L-chloroalanine. L-Chloroalanine, in addition to being a substrate, inhibits the dehydratase in a manner kinetically identical with that of L-serine.
As shown by viscosity and optical rotation dispersion measurements, subtilisin Carlsberg is not denatured in the presence of 10 M urea or 6 M guanidinium chloride. This unusual structural stability made it possible to investigate the effects of these hydrophobic-bond breaking solutes on various aspects of the enzymic interaction with substrates and inhibitors. The binding of the competitive inhibitor N-benzoylarginine was decreased by urea or guanidinium chloride. The nature of this effect was such as to implicate hydrophobic interaction as making a major contribution to the binding. By contrast, Ks for the substrates N-acetyltyrosine ethyl ester, N-benzoylarginine ethyl ester and N-trans-cinnamoylimidazole was apparently unchanged by the presence of urea or guanidinium chloride. The influence of these solutes on kcat for the substrates was rather involved. Tentative hypotheses are put forward to account for the effects seen.