P. putida Formaldehyde Dehydrogenase

Abstract

The P. putida formaldehyde dehydrogenase (P-FDH) [EC 1.2.1.46] (Ogushi, et al., 1984a) meets the operational criteria of an aldehyde dehydrogenase. When P-FDH is incubated with NAD⁺ and either formaldehyde or acetaldehyde it catalyzes the production of NADH as monitored by an increase in A₃₄₀, whereas no increase in A₃₄₀ is observed with propanal or longer chain aldehydes; thus, it is specific for short chain aldehydes. Furthermore, no decrease in A₃₄₀ is observed when aldehydes and NADH are incubated with P-FDH, nor is there any NADH generated with short chain primary alcohols and NAD⁺ (Ogushi, et al., 1984b; Ito, et al., 1994). P-FDH does show a weak, but measurable ability to dehydrogenate long chain primary alcohols, but only at high pH (Ogushi, et al., 1984b). While P-FDH nominally functions as an aldehyde dehydrogenase, it is a class III alcohol dehydrogenase (Kaiser, et al., 1988; Holmquist & Vallee, 1991; Danielsson, et al., 1994; Estonius, et al., 1994) based on sequence analysis, with an overall 26% sequence identity (42% similarity) to the human χ-ADH (Ito, et al., 1994), a class of ADHs that shows sequence similarities to the human class I ADHs (Danielsson, et al., 1994).