Isolation and characterization of a taurine‐specific opine dehydrogenase from the pedicles of the brachiopod, Glottidea pyramidata

Abstract

Tauropine dehydrogenase (pyruvate + taurine + NADH % tauropine + NAD+) was partially purified from the pedicles of the inarticulate brachiopod, Glottidea pyramidata. The molecular mass of this enzyme, as determined by high performance liquid chromatography (HPLC) using a TSK-3000 SW column, was 39,500 daltons. This molecular mass value is consistent with a monomeric structure characteristic of all opine dehydrogenases. Kinetic studies revealed that taurine and pyruvate were the preferred substrates, although other amino acids and keto acids were used to some extent. This enzyme readily oxidized tauropine displaying an apparent K, of 3.1 mM.Taurine was found to be the most abundant free amino acid in neutralized perchloric acid extracts of pedicles. Thus, it is likely that taurine is a physiological substrate. This enzyme shows striking similarities to tauropine dehydrogenases from archeogastropods.Marine invertebrate tissues exhibit a variety of' enzymatic mechanisms for maintaining cytoplasmic redox balance during anaerobiosis. Besides the classic NADH-dependent lactate and malate dehydrogenases, a completely new class of so-called opine dehydrogenases has been discovered. These enzymes are all characterized by their ability to catalyze the reductive condensation of pyruvate with an amino acid to form an unique imino acid end product known as an opine compound. The following three opine dehydrogenases have been identified in the tissues of certain marine invertebrates: Gade and Grieshaber, '86). Recently, a new opinelike compound was detected in extracts of the foot muscle of the abalone Haliotis discus hannai (Sato et al., '85)) which appeared to be structurally similar to the opines. This new opine was an imino acid derived from the condensation of pyruvate and taurine. Sat0 et al. ('85)

Purification and Characterization of Tauropine Dehydrogenase from the Marine Sponge <i>Halichondria japonica</i> Kadota (Demospongia)

“…With respect to the keto acid substrate specificity, the sponge TaDH slightly differs from the abalone enzymes and the brachiopod enzyme which exhibit rather narrow keto acid specificity and, surprisingly, do not utilize ox alacetate at all. [18][19][20] The utilization of several keto acids other than pyruvate has been reported in most of OpDHs.8) However, in general, keto acids other than pyruvate are taken as having no physiological meaning because of their relatively high (non-physiological) Km values. In the case of the sponge TaDH, however, we can not entirely neglect a physiological significance of the reaction involv ing oxalacetate, since the activity observed for oxalacetate is exceedingly high and the apparent Km for this keto acid is low.…”

The nutritional role of endosymbiotic bacteria in animal-bacteria symbioses : Solemya velum, a case study

“…In this context, taurine may affect the permeability of cardiac membranes to potassium and the shape of the action potential. In some archaeogastropods and brachiopods, pyruvic acid and taurine may undergo reductive condensation to yield tauropine (Sato et al, 1985;Doumen and Ellington, 1987). There is no evidence available in the literature to suggest that any of these processes are operating in marine bivalves; however, the existence of such functions for the excess taurine of S. velum cannot be ruled out.…”

“…Taurine may serve a variety of functions in marine invertebrates. Taurine may be used in energy storage by certain annelids and sipunculids (Thoai and Robin, 1965;Thoai and Roche, 1960); taurine may function to regulate the excitability of a variety of cell types Pasantes-Morales, 1982); in some archaeogastropods and brachiopods, pyruvic acid and taurine may undergo reductive condensation to yield tauropine (Sato et al, 1985;Doumen and Ellington, 1987).…”