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M Rippa

Publications and source records attributed to M Rippa.

At least 37 records · Page 2Linked to original sources
PubMed1981

Evidence for multiple pairs of vicinal thiols in some proteins.

The oxidizing agent periodate has been used as an analogue of phosphate. The reaction of periodate with some enzymes which have a phosphate-binding site causes only the formation of disulfide bridges and the loss of the catalytic activity. Phosphate and other tetrahedral anions protect against inactivation. Other enzymes are not inactivated by periodate, which seems to be specific for vicinal thiols. The results obtained suggest (a) the use of periodate for the detection of vicinal thiols in proteins, (b) the presence of multiple pairs of vicinal thiols in the proteins tested, and (c) the presence of these pairs at a phosphate-binding site. An hypothesis on the chemical structure of the phosphate-binding site of some proteins is advanced.

Alcohol Oxidoreductases↗
PubMed1979

Affinity labelling of the NADP+-binding site of glucose 6-phosphate dehydrogenase from Candida utilis.

1. Periodate-oxidized NADP+ inhibits the catalytic activity of glucose 6-phosphate dehydrogenase from Candida utilis, competing with NADP+. 2. Incubation of the enzyme with the coenzyme analogue causes partial reversible inactivation of the enzyme as a result of affinity labelling of the coenzyme-binding site. 3. Some kinetic values of the reaction were calculated. 4. The inactivation can be made irreversible by treatment with NaBH4, which reduces a Schiff base formed between an aldehyde group on the coenzyme analogue and a lysine residue on the enzyme. 5. Complete inactivation can be correlated with the binding of only one inhibitor to each enzyme subunit. 6. The lysine residue involved in the binding of the inhibitor is present at the coenzyme-binding site.

Affinity Labels↗