New Gaba-containing analogues of human growth hormone-releasing hormone (1-30)-amide: I. Synthesis and in vitro biological activity.
Analogues of human growth hormone-releasing hormone (1-30)-amide have been developed. All analogues have been modified in position 27 with Nle and with Gaba in position 30. Additional D-amino-acids have been inserted in the GHRH(1-30)-NH2 sequence: A-1741: Nle27,Gaba30-GH-RH(1-30)-NH2 A-495: D-Ala2,Nle27,Gaba30-GH-RH(1-30)-NH2 A-515: D Ala2,Leu15,Nle27,Gaba30-GH-RH(1-30)-NH2 A-527: D-Ala2,D-Arg11,Leu15,Nle27,Gaba30-GH-RH(1-30)-NH2. Our analogues were synthesized by solid phase peptide synthesis and were tested is two different in vitro systems and in rat pituitary cell cultures. A-495 and A-1741 were found to be the most active in releasing GH, however they showed different activities in the two different test systems. A-495 exhibited higher potency in the superfusion system (1.63 fold potency of the GHRH (1-29)-amide), while A-1741 evoked higher GH release from cultured pituitary cells (1.5-2.5 times higher than the GH-RH(1-44)-amide). The other analogues (A-515 and A-527) were found to be equipotent to the standard molecule. We can conclude that Nle27 and Gaba30 substitutions appeared to be a good modification in in vitro test systems, and Gaba30 substitution served as a good spacer during the synthesis, since it made the coupling of the C-terminal amino acids easier and produced quantitative coupling. In addition to the advantageous properties in the synthesis these modifications with or without D-Ala at the N-terminus increased the in vitro biological activity to 1.5-2.5 fold of the GHRH molecule.(ABSTRACT TRUNCATED AT 250 WORDS)
Mezö
I
I
Semmelweis University Medical School, Budapest, Hungary.
Kovács
M
M
Szöke
B
B
Szabó
E Z
EZ
Horváth
J
J
Makara
G B
GB
Rappay
G
G
Tamás
J
J
Teplán
I
I
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D013007:Growth Hormone-Releasing Hormone / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D016339:Spectrometry, Mass, Fast Atom Bombardment; D005680:gamma-Aminobutyric Acid / Q000737:chemistry*
C086561:somatotropin-releasing hormone (1-30) amide; D005680:gamma-Aminobutyric Acid; D013007:Growth Hormone-Releasing Hormone