Active Group of Papain
نویسندگان
چکیده
منابع مشابه
Studies on the active--SH group of papain and on the mechanism of papain activation by thiols.
It is now generally agreed that papain possesses a single reactive sulfhydryl group which is essential for activity and which probably participates in the catalytic mechanism by forming acyl intermediates with the different substrates (2, 3). Smith (4) has claimed that the essential sulfhydryl group of papain is kinetically more active than most protein sulfhydryl groups and that it possesses d...
متن کاملIsolation and characterization of an enzymically active fragment of papain.
Evidence has been presented earlier (2, 3) that leucine aminopeptidase can degrade about two-thirds of the molecule of mercuripapain, liberating free amino acids, without altering the enzymic activity of the papain when it is reactivated. Although several experimental results supported this conclusion, the best evidence came from two types of observations: first, new amino end groups different ...
متن کاملReaction of the sulfhydryl group of papain with chloroacetic acid.
The kinetics of the alkylation of the essential sulfhydryl group of papain with chloroacetic acid was studied. The variation of the second order rate constant with pH at 4.5” and 30.5’, r/2 = 0.07, is bell-shaped, with rate constants at a maximum near neutrality, approaching zero at low pH, and approaching a positive minimum at high pH. These profiles are described by a formulation which relate...
متن کاملEvidence for histidine in the active site of papain.
Papain was irreversibly inhibited by 1,3-dibromoacetone, a reagent designed to react first with the active-site cysteine residue and subsequently with a second nucleophile. The molecular weight of the inhibited enzyme was indistinguishable from that of papain itself, and no evidence of dimeric or oligomeric species was found. The optical-rotatory-dispersion curves of chloroacetone-inhibited pap...
متن کاملFluorescence energy transfer studies on the active site of papain.
Measurements have been performed of the excited-state lifetimes and fluorescence yields of papain tryptophan units when acyl derivatives of Phe-glycinal are bound at the active site of the enzyme. The enhancement of tryptophan fluorescence in complexes of papain with the acetyl or benzyloxycarbonyl derivatives is not stereospecific with respect to the configuration of the phenylalanyl residue, ...
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ژورنال
عنوان ژورنال: Nature
سال: 1938
ISSN: 0028-0836,1476-4687
DOI: 10.1038/142539a0