Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.22.6 (chymopapain)
 407 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chymopapain (Discase) was injected at a dose of 0.125 nanokatal unit into the intervertebral discs of rabbits, and sequential changes in the metabolism of water, proteoglycan, collagen, and noncollagenous protein were investigated separately in the nucleus pulposus, anterior, and posterior anulus fibrosus. One week after chymopapain injection, the water and proteoglycan content was lower in all of the fractionated tissues of the anterior and posterior anulus and nucleus pulposus of the discs than in the control discs. In the anterior and posterior anulus, the proteoglycan content recovered after 12 weeks, but there was no recovery in the nucleus pulposus. The collagen content continued to increase up to the 12th week in the nucleus pulposus, while the noncollagenous protein content decreased in all tissue fractions after 1 week. In the anterior and posterior anulus, the content of noncollagenous protein recovered after 3 to 6 weeks, but there was no recovery in the nucleus pulposus. The lysine incorporation in collagen and noncollagenous protein was inhibited in all tissue fractions after 12 weeks, suggesting a decrease in synthetic activity. The intradiscal pressure calculated from proteoglycan hydration at 1 to 6 weeks after chymopapain injection showed a marked decrease to 0.8 to 0.9 atm, but it recovered to 1.6 atm after 12 weeks.
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PMID:Water, fixed charge density, protein contents, and lysine incorporation into protein in chymopapain-digested intervertebral disc of rabbit. 251 52

Chymopapain A was isolated from the dried latex of papaya (Carica papaya) by ion-exchange chromatography followed by covalent chromatography by thiol-disulphide interchange. The latter procedure was used to produce fully active enzyme containing one essential thiol group per molecule of protein, to establish that the chymopapain A molecule contains, in addition, one non-essential thiol group per molecule and to recalculate the literature value of epsilon 280 for the enzyme as 36 000 M-1 X cm -1. The Michaelis parameters for the hydrolysis of L-benzoylarginine p-nitroanilide and of benzyloxy-carbonyl-lysine nitrophenyl ester at 25 degrees C, and I 0.1 at several pH values catalysed by chymopapain A, papaya proteinase omega, papain (EC 3.4.22.2) and actinidin (EC 3.4.22.14) were determined. Towards these substrates chymopapain A has kcat./km values similar to those of actinidin and of papaya proteinase omega and significantly lower than those of papain or ficin. The environment of the catalytic site of chymopapain A is markedly different from those of other cysteine proteinases studied to date, as evidenced by the pH-dependence of the second-order rate constant (k) for the reaction of the catalytic-site thiol group with 2,2'-dipyridyl disulphide. The striking bell-shaped component that is a characteristic feature of the reactions of S-/ImH+ (thiolate/imidazolium) ion-pair components of many cysteine-proteinase catalytic sites with the 2,2'-dipyridyl disulphide univalent cation is not present in the pH-k profile for the chymopapain A reaction. The result is consistent with the presence of an additional positive charge in, or near, the catalytic site that repels the cationic form of the probe reagent. Resonance Raman spectra were collected at pH values 2.5, 6.0 and 8.0 for each of the following dithioacyl derivatives of chymopapain A: N-benzoylglycine-, N-(Beta-phenylpropionl)glycine- and N-methoxycarbonylphenylalanylglycine-. The main conclusion of the spectral study is that in each case the acyl group binds as a single population known as conformer B in which the glycinic N atom is in close contact with the thiol S atom of the catalytic-site cysteine residue, as is the case also for papain and other cysteine proteinases studied. Thus the abnormal catalytic-site environment of chymopapain A detected by the reactivity-probe studies, which may have consequences for the acylation step of the catalytic act, does not perturb the conformation of the bound acyl group at the acyl-enzyme-intermediate stage of catalysis.
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PMID:Chymopapain A. Purification and investigation by covalent chromatography and characterization by two-protonic-state reactivity-probe kinetics, steady-state kinetics and resonance Raman spectroscopy of some dithioacyl derivatives. 351 53