Amino acid sequence of beta-galactosidase. IV. Sequence of an alpha-complementing cyanogen bromide peptide, residues 3 to 92.
Intracistronic alpha-complementation between a cyanogen bromide digest of beta-galactosidase and an extract of the lac Zminus operator-proximal deletion mutant M15 was used to monitor the purification of a cyanogen bromide peptide (CB2) responsible for the complementation. Key steps in the purification were ion exchange chromatography on carboxymethylcellulose and sulfopropyl-Sephadex in the presence of urea, and Sephadex gel filtration. CB2 contains residues 3 to 92 of beta-galactosidase. Its sequence is: Ile-Thr-Asp-Ser-Leu-Ala-Val-Val-Leu-Gln-Arg-Arg-Asp-Trp-Glu-Asn-Pro-Gly-Val-Thr-Gln-Leu-Asn-Arg-Leu-Ala-Ala-His-Pro-Pro-Phe-Ala-Ser-Trp-Arg-Asn-Ser-Glu-Glu-Ala-Arg-Thr-Asp-Arg-Pro-Ser-Gln-Gln-Leu-Arg-Ser-Leu-Asn-Gly-Glu-Trp-Arg-Phe-Ala-Trp-Phe-Pro-Ala-Pro-Glu-Ala-Val-Pro-Glu-Ser-Trp-Leu-Glu-Cys-Asp-Leu-Pro-Glu-Ala-Asp-Thr-Val-Val-Val-Pro-Ser-Asn-Trp-Gln-Met. Thus no more than 1/13 of the beta-galactosidase polypeptide chain, starting 2 residues from the NH2 terminus, is necessary for alpha-complementation with M15 as alpha-acceptor.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D002918:Chymotrypsin; D003488:Cyanogen Bromide; D004589:Electrophoresis, Disc; D004926:Escherichia coli / Q000201:enzymology; D005696:Galactosidases; D005816:Genetic Complementation Test; D009154:Mutation; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin; D014508:Urea
D000596:Amino Acids; D010446:Peptide Fragments; D014508:Urea; D005696:Galactosidases; D002918:Chymotrypsin; D014357:Trypsin; D003488:Cyanogen Bromide