Cleavage of nicotinamide adenine dinucleotide by the ribosome-inactivating protein from Momordica charantia.

ABSTRACT: The interaction of momordin, a type 1 ribosome-inactivating protein from Momordica charantia, with NADP(+) and NADPH has been investigated by X-ray diffraction analysis of complexes generated by co-crystallization and crystal soaking. It is known that the proteins of this family readily cleave the adenine-ribose bond of adenosine and related nucleotides in the crystal, leaving the product, adenine, bound to the enzyme active site. Surprisingly, the nicotinamide-ribose bond of oxidized NADP(+) is cleaved, leaving nicotinamide bound in the active site in the same position but in a slightly different orientation to that of the five-membered ring of adenine. No binding or cleavage of NADPH was observed at pH 7.4 in these experiments. These observations are in accord with current views of the e

SUBMITTER: Vinkovic M 

PROVIDER: S-EPMC4555922 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature