TABLE 2.

d-Amino acid dehydrogenase levels in wild-type and lrp mutants of K. aerogenes and E. coli

Straina	Relevant genotype	Dehydrogenase level obtained withb:
		0 mM l-alanine	100 mM l-alanine
KC3346	Wild type	9 ± 2	222 ± 9
KC4602	lrp-101	40 ± 6	53 ± 5
W3110	Wild type	24 ± 4	292 ± 24
BE2	lrp-35::Tn10	31 ± 1	63 ± 3

^aKC3346 and KC4602 are K. aerogenes strains derived from strain W70. W3110 and BE2 are E. coli strains derived from strain K-12. 

^bThe growth medium was comprised of W4 salts (4) supplemented with glucose (0.4%), ammonium sulfate (0.2%), l-glutamine (0.2%), l-leucine, l-isoleucine, l-valine, l-serine (0.005%), and l-alanine as indicated. Cultures of KC4602 also contained ampicillin at 100 μg/ml to maintain the lrp-101 allele, while those of BE2 contained tetracycline at 30 μg/ml to maintain the lrp-35::Tn10 allele. Enzyme activity is reported as specific activity (units per milligram of protein), and values are the means and standard errors of the means of at least three independent experiments. The assays were performed as described previously (15).