The role of the nicotinamide and adenine subsites in the negative co-operativity of coenzyme binding to glyceraldehyde-3-phosphate dehydrogenase

Yoav I. Henis*, Alexander Levitzki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The interaction of 3-aminopyridine-adenine dinucleotide, an NAD + † analogue which is fluorescent at the pyridine end of the molecule, with rabbit muscle glyceraldehyde-3-phosphate dehydrogenase was investigated. The fluorescence properties of the AAD+ molecule were used to monitor the nicotinamide subsites ou the GPDHase tetramer, the fluorescent aminopyridine moiety of the molecule serving as an intrinsic probe. Although the binding of AAD+ wag found to be negatively co-operative, no conformational changes induced at the nicotinamide subsite upon coenzyme binding were found to be transmitted to neighboring subunits. These findings, in conjunction with our earlier findings and with the observation that different NAD+ analogues which differ in the chemistry of the pyridine moiety bind with different extents of co-operativity, enable us to offer specific roles for the nicotinamide and the adenine subsites in generating the negative co-operativity. It is suggested that the structure of the pyridine moiety of the coenzyme controls the mode of binding of the pyridine moiety to the nicotinamide subsite. This, in turn, controls the orientation of the adenine moiety with respect to its subsite, thereby determining the mode of the interactions between the adenine and its binding domain. As the propagation of conformational changes caused by these interactions to neighboring subunits is believed to be the cause of the negative co-operativity exhibited by this enzyme towards coenzyme binding, the structure of the pyridine moiety controls this phenomenon.

Original languageEnglish
Pages (from-to)699-716
Number of pages18
JournalJournal of Molecular Biology
Volume117
Issue number3
DOIs
StatePublished - 15 Dec 1977
Externally publishedYes

Funding

FundersFunder number
United States-Israel Binational Science Foundation

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