Document Detail

Physico-chemical properties of pregnant mare serum gonadotropin.
MedLine Citation:
PMID:  6783116     Owner:  NLM     Status:  MEDLINE    
Pregnant mare serum gonadotropin exhibits a dissociation at acid pH as shown by the drop of s20,w values from 3.52 S at pH 8.1 to 2.52 S at pH 2.0. The dissociation is accompanied by an absorbance change with a maximum at 287 nm and a parallel loss of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activities as followed by radioreceptor assays. The apparent pKa of the acid transition is 3.45 with an extremely slow and temperature-dependent rate at pH 2.0 (1.8 . 10(-4) s-1 at 37 degrees C). By gel filtration the molecular weight of the active hormone is estimated to be 45 000 (rather than the previously reported 53 000-64 000). The active conformation of the hormone includes beta sheet structure (34%) as for other gonadotropin hormones with a minor but significative amount of alpha-helix. Four tyrosine residues were titrated, two of pKa = 10.3 and two of pKa = 11 out of a total of seven tyrosines. The parallel changes in FSH and LH activities during the preparation and the acid transition suggest that the two biological activities are intrinsic properties of the same molecular entity.
Y Combarnous; R Salesse; J Garnier
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  667     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1981 Feb 
Date Detail:
Created Date:  1981-06-25     Completed Date:  1981-06-25     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  267-76     Citation Subset:  IM    
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MeSH Terms
Chemical Phenomena
Circular Dichroism
Follicle Stimulating Hormone / pharmacology
Gonadotropins, Equine / pharmacology*
Hydrogen-Ion Concentration
Luteinizing Hormone / pharmacology
Molecular Weight
Protein Conformation
Reg. No./Substance:
0/Gonadotropins, Equine; 9002-67-9/Luteinizing Hormone; 9002-68-0/Follicle Stimulating Hormone

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