Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00631 (Gel)
 14,881 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chemical modification of two new double-headed-protease inhibitors from black-eyed peas, a trypsin-chymotrypsin inhibitor (BEPCI) and a trypsin inhibitor (BEPTI) with dansyl chloride was investigated under various conditions. The NH2-terminal serine of both BEPCI and BEPTI, the 4 lysyl residues of BEPCI, and 4 of the 5 lysyl residues of BEPTI, could not be dansylated in the absence of urea. The single tyrosine per subunit of BEPCI and BEPTI was unreactive even in the presence of urea but could be labeled with half-site reactivity by the Celite method. Lysine, NH2-terminal serine, and tyrosine were reactive in fully reduced, carbamidomethylated BEPCI and BEPTI. Gel filtration was used to study the subunit interactions of BEPCI and BEPTI. At pH 8 or pH 3.0 there is a complex set of multiple equilibria with widely differing rates of attainment. We have found evidence for a rapid dimer-tetramer equilibrium, a distinct moderate rate dimer-tetramer equilibrium, a very slow monomer-dimer equilibrium, and postulate slow isomerization of the two forms of dimer and the two forms of tetramer. The monomer-dimer equilibrium is quite unusual in that the dimer is stabilized by chaotropic ions and even slightly by guanidine HC1. In contrast to the complex pattern seen in native BEPCI, the half-site, dansylated BEPCI exists at similar concentration exclusively as a tetramer at neutral pH.
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PMID:Double-headed protease inhibitors from black-eyed peas. III. Subunit interactions of the native and half-site chemically modified proteins. 0 94

The reaction products of peroxidase, a hydrogen donor and hydrogen peroxide decreased the amount of lysine recovered from proteins after acid hydrolysis. Oxidation of peroxidase treated proteins with performic acid prior to hydrolysis formed alpha-amino adipic acid indicating that the peroxidase or the quinones formed by peroxidase had oxidatively deaminated some lysyl residues of the protein to form lysyl aldehyde. Gel filtration and polyacrylamide gel electrophoresis revealed dimers, trimers and higher protein polymers that were not detected when peroxidase was omitted. Since some of the protein polymers were not dissociated by gel electrophoresis in the presence of dodecyl sulfate, urea and mercaptoethanol, it suggests that the free radicals or quinones formed by peroxidase had interacted with or cross-linked protein molecules by the formation of covalent bonds. Oxidative enzymes like peroxidase and polyphenol oxidase may lower the nutritive value of proteins by the oxidative deamination of lysine, reaction with cysteine and methionine and by cross-linking protein molecules to reduce their susceptibility to enzymatic hydrolysis.
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PMID:Cross-linking of protein by peroxidase. 2 Jul 49

Feather (keratinous) protein isolates containing 2.8 and 7.2% half-cystine were prepared. Solubility of the former increased to 100% between pH 6 and 12, whereas, that of the latter reached only 2.5% at pH 12. Tests showed that mixtures of sodium dodecyl sulfate and 2-mercaptoethanol were needed to completely solubilize the high half-cystine protein, and that sodium dodecyl sulfate alone or in combination with urea and/or 2-mercaptoethanol increased solubilization of the low half-cystine product. The rates of these reactions are further increased by heat. Dry heat denatured the low half-cystine isolate more readily than the high half-cystine product; moist heat denatured both at a similar rate. Gel electrophoretic properties were unique for each keratinous product. Only the low half-cystine isolate ahd desirable functional properties in that it formed thick, viscous mayonnaise-like emulsions and desirable foams. Functional properties of this isolate were improved dramatically by adjusting the pH from 5.0 to 8.2 or by a two-step change from pH 5.0 to 4.0 to 8.2. Apparent nitrogen digestibility of the two keratinous isolates was greater than 90% as measured by rat growth and by pepsin-HCl digestion.
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PMID:Some chemical and nutritional properties of feather protein isolates containing varying half-cystine levels. 2 Jul 52

The presence of two cysteine residues per each six monomers comprising the oligomer of Chlorella glutamine synthetase (E.C.6.3.1.2) is demonstrated using homogenous enzyme preparation. p-Chloromercuribenzoate (p-CMB) is found to inhibit glutamine synthetase activity, the degree of inhibition depending on the inhibitor concentration. The following enzyme reactivation by dithiotreitol (10(-2) M) was observed only when the enzyme was inactivated with 10(-5) M p-CMB under 15 min. preincubation. Preincubation of the enzyme with 10(-4) M p-CMB for 45 min. did not result in its reactivation. Gel filtration of glutamine synthetase treated with 10(-4) M p-CMB has revealed the dissociation of the enzyme into inactive monomers. Incubation of glutamine synthetase with p-CMB at various pH values, incubation after pre-treatment with urea and experiments with HgCl2 indicate the presence of free and masked inside the globula SH-groups in the enzyme molecule. Competitive character of the enzyme inhibition with p-CMB with respect to ATP indicates that SH-groups of the active site participate in the ATP binding, probably, as Mg-ATP or Mn-ATP complexes. Data on the estimation of ionization constant of glutamate-binding group and experiments on the effect of histidine photooxidation on the enzyme activity indicate the presence of histidine residue in the enzyme active site, which participates in glutamate binding.
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PMID:[Presence of SH-groups and histidine in the active site of Chlorella glutamine synthetase]. 2 48

Human cataractous lenses from subjects aged 20-91 years were extracted in tris/glycine buffer and fractionated on Sephadex G-75 column. Four fractions, F1, F2, F3 and F4 identified as alpha-, beta1-, beta2- and gamma-crystallin were obtained. Gel electrophoresis of alpha-crystallin in polyacrylamide containing 6M urea revealed changes in polypeptide composition, colouration; variation in band pattern and mean mobility. The relative mobilities of the protein bands were used to calculate coefficient of similarity within the same age group and among different age groups.
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PMID:Variations in the soluble alpha-crystallin proteins from human cataractous lenses. 9 55

Thyroglobulin samples were prepared individually be gel chromatography from the thyroids of five persons without thyroid disease and four with goiters. Gel electrophoresis at different pHs and gel concentrations showed a single major band corresponding to 19S thyroglobulin in rabbits, with occasional faint bands corresponding to 12S and 27S species. The thyroglobulins of the normals differed from each other in electrophoretic pattern on sodium dodecyl sulfate (SDS)-urea gels and in composition of iodine, monosaccharides, and amino acids. Nine amino acids showed significant variation among the five thyroglobulins at the P less than 0.01 level, and only two (lysine and alanine) did not vary. The content of both sialic acid and fucose varied widely, but their sum was similar among the five samples. Thyroglobulin samples from the goiters differed from the normals and from each other in composition and in pattern on SDS-urea gels. The variability itself was more impressive than were differences in any particular component. Relative to the normals, these thyroglobulins showed increases in content of sialic acid (P less than 0.01) and lysine (P less than 0.10), and increases in the faster bands on gel electrophoresis in SDS-urea. Two goiters were from patients with the multiple hamartoma syndrome, and the only metabolic abnormality found was a low content of iodothyronine in thyroglobulin. The other two goiters also showed inadequate coupling of iodotyrosyls. In addition, one contained a soluble iodoprotein of very high molecular weight, which was immunologically identical to 19S thyroglobulin but differed in chemical composition. We conclude from the compositional data that there is not a single structure for "normal" thyroglobulin, but that multiple molecular configurations occur naturally and are compatible with adequate hormone synthesis. Extensive variations in thyroglobulin structure are frequently found with goiter, and we suggest that these may be involved in its pathogenesis.
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PMID:Variations in the structure of thyroglobulins from normal and goitrous human thyroids. 12 14

The gel-electrophoretic pattern of dissociated proteoglycans was studied in 7 fetuses, 5 premature newborns, 4 term newborns, 5 infants and 5 children. The tibial growth cartilage was extracted with 4 M guanidinium chloride. After dialysis against 8 M urea at pH 7 the proteoglycans were obtained by ion chromatography in urea on DEAE cellulose and submitted to gel electrophoresis on polyacrylamide agarose gels. Gel electrophoresis of proteoglycans showed a different pattern in fetuses from that found in children. The change occurs in the first months of extrauterine life.
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PMID:Age-dependent change in the gel-electrophoretic pattern of proteoglycans of human growth cartilage. 12 91

An anomalous zymogram of lactate dehydrogenase (LDH) in the serum from a patient with liver cirrhosis was reported. Agar-gel electrophoresis of serum showed an extra LDH band close to the anodic side of LDH5 and a wide band of LDH5. Gel filtration of patient's serum in Sephadex G-200 demonstrated an abnormal LDH fraction eluted between immunoglobulin G (IgG) and macroglobulin in addition to a normal LDH component. Chromatographically abnormal LDH was demonstrated on agar gel as extra and wide LDH5 bands and resembled closely human hepatic LDH in various physico-chemical properties such as inhibition by urea or substrate, stability against heat, and Michaelis-Menten's constant. Immunological analyses demonstrated that abnormal LDH could be in the state combined with IgG. Molecular weight of the complex estimated by gel filtration was approximately 300,000. Mixtures of the heated patient's serum with normal or patient's hepatic LDH showed abnormal LDH fraction by gel filtration, whereas abnormal fraction was not demonstrated when heated normal serum was mixed with normal or the patient's hepatic LDH. These results strongly suggest that the occurrence of anomalous LDH zymogram in patient's serum is due to a formation of LDH-IgG complex, which is based on the binding of essentially normal hepatic LDH and abnormal IgG.
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PMID:Macromolecular lactate dehydrogenase linked to serum IgG of a patient with liver cirrhosis. 13 87

Cultures of foetal human pituitary cells excrete and synthetize different molecular forms of proteins with HGH immunological activity. These cells incorporate tritiated-leucine in these proteins. Gel chromatography on sephadex using different length of column allow us to separate: One form excluded in front of the dead volume and which has a high molecular weight. This form is not dissociated by treatment with urea 8 M, guanidine 6 M and dithiothreitol. Nor this form is modified by treatment by ribonuclease. One form excluded within the dead volume and which is probably a dimere. This form is no more modified by the different treatments. One form which is excluded like a monomere--it is the more important form--. This form is dissociated in fragments of lower molecular weight by urea 8 M. This dissociation is partially reversible by dialysis.
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PMID:[Molecular forms of human growth hormone (HGH) secreted by cultured fetal pituitary cells]. 14 Jul 46

Reconstituted complexes of DNA with histone were prepared by salt-and-urea step gradient dialysis. The DNA was complexed with histone H1, with the combination of the other four histones H2A, H2B, H3 and H4, and with whole histones. These DNA-histone complexes were purified by Bio-Gel column chromatography, and the weight ratio of histone-to-DNA was determined in each complex. The thermal denaturation profile and nuclease digestion pattern of DNA-histone H2A, H2B, H3 and H4 complex were compatible with those of the polynucleosome structure of chromatin. The template activities for transcription were compared in these DNA-histone complexes by separately measuring initiation reaction and chain elongation. The binding of histone H1 to DNA strongly inhibited the initiation, while the binding of the combination of the other four histones to DNA partially inhibited the initiation and chain elongation. The binding characteristics are discussed with regard to the role of histone H1 and the other four histones in chromatin structure and template activity.
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PMID:Thermal denaturation and template activities of reconstituted DNA-histone complexes. 14


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