Identification of subunit contact sites on the alpha-subunit of lutropin.
Peptides corresponding to the entire sequence of the alpha-subunit of the human glycoprotein hormones were synthesized by using standard solid-phase procedures. Purified peptides were incubated in the presence of alpha- and beta-subunits of bovine lutropin, and subunit recombination was monitored by difference spectroscopy, reverse-phase high-pressure liquid chromatography, and gel filtration chromatography. Although the binding of alpha-peptides to either subunit could not be detected by these techniques, it was possible to demonstrate that some peptides could inhibit the recombination of alpha- and beta-subunits. Specifically, alpha-peptide 33-58 allowed only 0-11% of subunit recombination in 24 h (38-56% after 48 h), while alpha-peptide 51-65 allowed 10-60% of subunits to recombine in 24 h (65-94% in 48 h). Peptides 1-15, 11-27, 22-39, 61-78, and 73-92 of the alpha-subunit could not inhibit subunit recombination at any time or at any concentration tested. The data suggest that at least a portion of the alpha-subunit contact site has been identified, and results are discussed in terms of protein structure assessment tools.
Krystek
S R
SR
Department of Biochemistry A-10, Albany Medical College, New York 12208.
Dias
J A
JA
Andersen
T T
TT
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003198:Computer Simulation; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit / Q000138:chemical synthesis / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis; D011487:Protein Conformation; D013053:Spectrophotometry
D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D010455:Peptides; D005640:Follicle Stimulating Hormone