Glyceryl-ether monooxygenase [EC 1.14.16.5]. Part 9. Stereospecificity of the oxygenase reaction

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism

“…1.6. 140,232 The formation of the carbon-oxygen bond can occur with retention or inversion of configuration at C1Ј, but this cannot be deduced from these experiments and should await the isolation of the intermediate hemiacetal (see Scheme 1). However, by analogy with the known stereospecificities of hydroxylations by mixed function monooxygenases, all of which occurred with retention of configuration, [233][234][235][236][237] the hydroxylation by glyceryl-ether monooxygenase can tentatively be said to occur with retention of configuration at C1Ј of the glyceryl ethers.…”

“…187,222 Since all the kinetic parameters determined by the direct spectrophotometric assay involved initial rates measurements, i.e., within the first 2 mins, all the data obtained by this assay were valid. 31,138,140,191,192,194 It should be noted that in the radiometric assay the amount of octadecanol and octadecanoic acid formed were about the same, and as no pyridine nucleotide was added then the small amount of it bound to membrane oxidoreductases must have recycled to produce these products from octadecanal. The increased amounts of 6-MePH 4 consumed after ca.…”

“…Although the molecular ion peaks of the free alcohols were weak, the M -CH 3 Oи ϩ peaks after loss of the terminal CH 2 OH, were intense and could be compared with the related peak (with one mass unit less) of the unlabeled fragment which appeared in the same spectrum. 140 ␣-Alkyl glyceryl ethers but not the ␤-ethers have optical rotatory properties because of the chiral center at C2 (see 2) (Sec. I-A).…”

“…With this assay it was possible to measure kinetic parameters with the usual accuracy (Ϯ5-10%). 31,138,140,191,194,220 …”

Dedication to Desmond Joseph Brown

“…After 1973, he encouraged me in my new ventures of investigating ubiquitous reduced pteridine cofactors of three aromatic acid hydroxylases and the relevant reductase, [45,46] as well as ether-lipid monooxygenase. [47,48] Deficiency in these enzymes results in birth defects in children. This work required enzyme purification, enzyme kinetics, and later, DNA cloning in order to express enzymes with mutations found in affected children.…”