Semisynthesis of human growth hormone-releasing factor by trypsin catalyzed coupling of leucine amide to a C-terminal acid precursor.
Human growth hormone-releasing factor, GRF(1-44)-NH2, was synthesized by trypsin catalyzed coupling of Leu-NH2 to Arg43 of the precursor, GRF(1-43)-OH, prepared by solid phase peptide synthesis. The semisynthetic GRF(1-44)-NH2 was fully characterized and showed full potency in the rat pituitary in vitro bioassay. Conversion to GRF(1-44)-NH2 was limited to 60-70% in both 75% v:v N,N'-dimethylacetamide and 95% v:v 1,4-butanediol due to competing transpeptidations at Arg41 and Arg38 generating [Leu42]-GRF(1-42)-NH2 and [Leu39]-GRF(1-39)-NH2 side-products, respectively. The rates of formation and yields of GRF(1-44)-NH2 versus pH, Leu-NH2 concentration, and solvent composition were also studied.
Bongers
J
J
Department of Peptide Research, Roche Research Center, Hoffmann-La Roche Inc., Nutley, New Jersey.
Offord
R E
RE
Felix
A M
AM
Campbell
R M
RM
Heimer
E P
EP
D000595:Amino Acid Sequence; D002384:Catalysis; D013007:Growth Hormone-Releasing Hormone / Q000138:chemical synthesis* / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives* / Q000737:chemistry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D014357:Trypsin
D010446:Peptide Fragments; C045269:somatotropin releasing hormone (1-43); D013007:Growth Hormone-Releasing Hormone; D014357:Trypsin; D007930:Leucine; C013086:leucinamide