In the absence of acceptors nucleoside 2-deoxyribosyltransferase catalyzes the slow hydrolysis of 2'-deoxynucleosides. During this hydrolytic reaction, D-ribal (1,4-anhydro-2-deoxy-D-erythro-pent-1-enitol), a glycal of ribose hitherto encountered only as a reagent in organic synthesis, is generated spontaneously, disappearing later as 2'-deoxynucleoside hydrolysis approaches completion. Nucleoside 2-deoxyribosyltransferase is found to catalyze the hydration of D-ribal in the absence of nucleic acid bases and the synthesis of deoxyribonucleosides from ribal in their presence, affording a new method for the preparation of 2'-deoxyribonucleosides. The stereochemistry of nucleoside formation from ribal supports the intervention of deoxyribosyl-enzyme intermediate. The equilibrium constant for the covalent hydration of ribal is found to be approximately 65.

A series of 5-substituted-1,3-dioxo-1H-benz[de]isoquinoline-2(3H)-acetic acid analogues have been examined as irreversible inhibitors of aldose reductase. The 5-alpha-bromoacetamide and 5-alpha-iodoacetamide analogues 5 and 6 gave irreversible inhibition of aldose reductase while the 5-alpha-chloroacetamide analogue 3 did not show this type of inhibition. Protection studies indicate that irreversible inhibitions are occurring at the inhibitor binding site. Comparative irreversible inhibition studies with rat lens aldose reductase (RLAR) and rat kidney aldehyde reductase (RKALR) indicate that 5-alpha-haloacetamide analogues 5 and 6 are much more effective inhibitors of RLAR.