Preparation of an Alcohol‐Dehydrogenase–NAD(H)–Sepharose Complex Showing No Requirement of Soluble Coenzyme for Its Activity

Abstract

Horse liver alcohol dehydrogenase and an NADH analogue, N6‐[(6‐aminohexyl)carbamoylmethyl]‐NADH, have been co‐immobilized to Sepharose 4B under conditions permitting binary complex formation between the enzyme and the cofactor. The enzyme‐coenzyme‐matrix preparations were assayed with a coupled oxidoreduction reaction and showed activities, prior to addition of coenzyme, that were up to 40% of that obtained in excess of free coenzyme. A molar ratio of 1:1 between the amount of bound nucleotide and bound enzyme was sufficient to obtain high activities in the absence of free coenzyme. The highest recycling rate obtained for the immobilized nucleotide was 3400 cycles per hour. Both thermal and storage stability of alcohol dehydrogenase was increased when the enzyme was co‐immobilized with the NADH analogue. The efficiency of the immobilized preparations (measured as product formation per minute and per assay volume) was higher (1.4 to 5 times in our assays) than the corresponding systems of free enzyme (in total enzyme units) and nucleotide in an identical assay volume. Copyright © 1975, Wiley Blackwell. All rights reserved