PMID:33657

Blackwell, CM and Turner, JM (1978) Microbial metabolism of amino alcohols. Purification and properties of coenzyme B12-dependent ethanolamine ammonia-lyase of Escherichia coli.Biochem. J. 175:555-63

Abstract

1. The 120-fold purification of ethanolamine ammonia-lyase from Escherichia coli extracts, to apparent homogeneity, is described. Ethanolamine, dithiothreitol, glycerol and KCl protected the apoenzyme from inactivation. 2. At the optimum pH7.5, K(m) values for ethanolamine and coenzyme B(12) were 44mum and 0.42mum respectively. The K(m) for ethanolamine was markedly affected by pH, transitions occurring at pH7.0 and 8.35. 3. The enzyme was specific for ethanolamine as substrate, none of the 18 analogues tested being active. l-2-Aminopropan-l-ol (K(i) 0.86mum), dl-1-aminopropan-2-ol (K(i) 2.2mum) and dl-1,3-diaminopropan-2-ol (K(i) 88.0mum) inhibited competitively. 4. Enzyme activity was inhibited, irreversibly and non-competitively, by the coenzyme analogues methylcobalamin (K(i) 1.4nm), hydroxocobalamin (K(i) 2.1nm) and cyanocobalamin (K(i) 4.8nm). 5. Iodoacetamide inhibited in the absence of ethanolamine, but only slightly in its presence. p-Hydroxymercuribenzoate inhibited markedly even in the presence of ethanolamine. Dithiothreitol and 2-mercaptoethanol (less effectively) restored activity to the enzyme dialysed against buffer containing ethanolamine. 6. Although K(+) ions stabilized the enzyme during dialysis or storage, they were not necessary for activity. 7. Gel filtration showed the enzyme to be of high molecular weight, ultracentrifugal studies giving s(20,w) of 16.4 and an estimated mol.wt. 560400. The isoelectric point for the apoenzyme was approx. pH5.0. inhibited enzyme activity at concentrations above 1m (95% inhibition at 3m) and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis indicated protein subunits of mol.wt. 61400. 8. Immunological studies showed that the E.coli enzyme was closely related to those of other enterobacteria, but only distantly to that of Clostridium sp. A double precipitin band suggested that the apoenzyme may be made up of two protein components.

Links

PubMed

Significance

You can help EcoliWiki by summarizing why this paper is useful

Useful Materials and Methods

You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.

Annotations

Gene product	Qualifier	GO ID	GO term name	Evidence Code	with/from	Aspect	Notes	Status
edit table

EcoliWiki Links

Add links to pages that link here (e.g. gene, product, method pages)

References

See Help:References for how to manage references in EcoliWiki.