Mutational replacement of methionine by arginine in the S′1 substrate binding site of yeast carboxypeptidase
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Standard
Mutational replacement of methionine by arginine in the S′1 substrate binding site of yeast carboxypeptidase. / Bech, Lene M.; Nielsen, John; Winther, Jakob R.; Kielland-Brandt, Morten C.; Breddam, Klaus.
I: Carlsberg Research Communications, Bind 51, Nr. 6, 1986, s. 459-465.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Mutational replacement of methionine by arginine in the S′1 substrate binding site of yeast carboxypeptidase
AU - Bech, Lene M.
AU - Nielsen, John
AU - Winther, Jakob R.
AU - Kielland-Brandt, Morten C.
AU - Breddam, Klaus
PY - 1986
Y1 - 1986
N2 - Alkylation of Met-398 in the S′1 binding site of carboxypeptidase Y drastically reduces kcat for hydrolysis of peptides, presumably due to introduction of a positively charged sulfonium ion. In the present work a positive charge has been introduced by means of site-directed mutagenesis, exchanging Met-398 with the cationic arginyl residue. The mutagenesis was carried out in bacteriophage M13 on a subcloned fragment of PRC1, the structural gene for carboxypeptidase Y, using an oligonucleotide containing the desired mutation as primer for secondary strand synthesis in vitro. A clone was identified in which codon 398 of PRC1 (ATG) had been changed to AGG, and the mutated sequence was reintroduced into the original PRC1 gene context. The resulting plasmid was used to transform a yeast strain, carrying a deletion at the prc1 locus and the mutant enzyme was isolated by affinity chromatography. The kcat values for the hydrolysis of N-blocked dipeptide substrates with varying groups in the P′1 position were equally low as for the alkylated Met-398 derivatives, consistent with the expected effects of a positive charge in position 398. The kinetic parameters for the hydrolysis of ester and amide substrates were similar to those obtained with the enzyme alkylated with iodoacetamide.
AB - Alkylation of Met-398 in the S′1 binding site of carboxypeptidase Y drastically reduces kcat for hydrolysis of peptides, presumably due to introduction of a positively charged sulfonium ion. In the present work a positive charge has been introduced by means of site-directed mutagenesis, exchanging Met-398 with the cationic arginyl residue. The mutagenesis was carried out in bacteriophage M13 on a subcloned fragment of PRC1, the structural gene for carboxypeptidase Y, using an oligonucleotide containing the desired mutation as primer for secondary strand synthesis in vitro. A clone was identified in which codon 398 of PRC1 (ATG) had been changed to AGG, and the mutated sequence was reintroduced into the original PRC1 gene context. The resulting plasmid was used to transform a yeast strain, carrying a deletion at the prc1 locus and the mutant enzyme was isolated by affinity chromatography. The kcat values for the hydrolysis of N-blocked dipeptide substrates with varying groups in the P′1 position were equally low as for the alkylated Met-398 derivatives, consistent with the expected effects of a positive charge in position 398. The kinetic parameters for the hydrolysis of ester and amide substrates were similar to those obtained with the enzyme alkylated with iodoacetamide.
KW - binding sites
KW - Carboxypeptidase Y
KW - chemical modification
KW - kinetics
KW - protein engineering
KW - site-directed mutagenesis
KW - substrate specificity
U2 - 10.1007/BF02907318
DO - 10.1007/BF02907318
M3 - Journal article
AN - SCOPUS:51849181794
VL - 51
SP - 459
EP - 465
JO - Carlsberg Research Communications
JF - Carlsberg Research Communications
SN - 0105-1938
IS - 6
ER -
ID: 200970301