Selective oxidation of methionyl residues in the human recombinant secretory leukocyte proteinase inhibitor. Effect on the inhibitor binding properties.
Binding of the human recombinant secretory leukocyte proteinase inhibitor (SLPI) [native and with the methionyl residues at positions 73, 82, 94 and 96 of domain 2 oxidized to the sulfoxide derivative (Met(O) SLPI)] to bovine alpha-chymotrypsin (alpha-chymotrypsin) [native and with the Met192 residue converted to the sulfoxide derivative (Met(O) alpha-chymotrypsin)] as well as to native bovine beta-trypsin (beta-trypsin), which does not contain methionyl residues, has been investigated between pH 4.0 and 8.0, and between 10.0 degrees C and 30.0 degrees C, from thermodynamic and/or kinetic viewpoints. By increasing the number of oxidized methionyl residues present at the proteinase:inhibitor contact interface (from 0 to 3), the adducts investigated are increasingly destabilized and the relaxation time of the complexes into conformers less stable is enhanced. On the other hand, the selective oxidation of methionyl residues of SLPI and alpha-chymotrypsin, by reaction with chloramine T, does not affect the proteinase inhibition recognition mechanism. Therefore, even though conformational changes may occur in the conversion of native SLPI and native alpha-chymotrypsin to their Met(O) derivatives, a localized steric hindrance can be considered as the main structural determinant accounting for the reported results.
Tomova
S
S
Department of Biochemical Sciences, Alessandro Rossi Fanelli, University of Rome La Sapienza, Rome, Italy.
Cutruzzolà
F
F
Barra
D
D
Amiconi
G
G
Ascenzi
P
P
Djinović Carugo
K
K
Menegatti
E
E
Sarti
P
P
Schnebli
H P
HP
Bolognesi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002700:Chloramines / Q000494:pharmacology; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008715:Methionine / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism*; D053481:Secretory Leukocyte Peptidase Inhibitor; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics; D014105:Tosyl Compounds / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism
D002700:Chloramines; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D011993:Recombinant Fusion Proteins; C506814:SLPI protein, human; D053481:Secretory Leukocyte Peptidase Inhibitor; D015842:Serine Proteinase Inhibitors; D014105:Tosyl Compounds; C016300:chloramine-T; D008715:Methionine; D002918:Chymotrypsin; D014357:Trypsin