Abstract
This chapter discusses the assay, purification, and properties of sarcosine dehydrogenase and dimethylglycine dehydrogenase. Assay of the sarcosine and dimethylglycine dehydrogenase employs phenazine methosulfate and 2, 6-dichlorophenolindophenol (DCPIP). Sarcosine dehydrogenase and dimethylglycine dehydrogenase are found in the liver mitochondria of the rat, pig, rabbit, guinea pig, pigeon, and chicken. These enzyme activities are also present in microorganisms. Sarcosine dehydrogenase does not oxidize glycine, serine, monomethylaminoethanol, dimethylaminoethanol, choline, betaine, and threonine. Sarcosine dehydrogenase, but not dimethylglycine dehydrogenase, from mammalian liver mitochondria is inhibited reversibly and competitively by methoxyacetate and related acetates. The absorption spectra of the oxidized form of the purified enzymes show a major peak at 405–415 m μ and a broad shoulder in the region of 430–460 m μ . With sodium phosphate or pyrophosphate buffers of ionic strength 0.1, the pH optima of the sarcosine dehydrogenase and dimethylglycine dehydrogenase in the phenazine methosulphate (PMS)–DCPIP assay system are 8 and 8.5–9, respectively. The purified preparations of both the sarcosine and dimethylglycine dehydrogenases can be lyophilized, and the dry powders are stable for at least a week when stored at -4°.
Published Version
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