New angiotensin I isolated from a reptile, Alligator mississippiensis.
Angiotensin I (ANG I) of the American alligator Alligator mississippiensis was isolated from incubates of homologous plasma and kidney extract, and its amino acid sequence was determined as H-Asp-Arg-Val-Tyr-Val-His-Pro-Phe-Ala-Leu-OH. The presence of strongly hydrophobic alanine at position 9 is unusual among ANGs I sequenced to date. Since alanine can be converted to serine by a one-point mutation of the triplet nucleotides, the phylogenetic proximity of the alligator to birds, whose ANG I has serine at position 9, is confirmed by the chemical evolution of the hormone structure. The alligator [Asp1,Val5,Ala9] ANG I increased arterial blood pressure of conscious alligators, but it was no more potent than avian [Asp1,Val5,Ser9] ANG I. The alligator ANG I was also equipotent to the homologous ANG I in the quail and rat. It is concluded that substitutions at position 9 have little influence on the vasopressor activity of ANG I.
Takei
Y
Y
Department of Physiology, Kitasato University School of Medicine, Kanagawa, Japan.
Silldorff
E P
EP
Hasegawa
Y
Y
Watanabe
T X
TX
Nakajima
K
K
Stephens
G A
GA
Sakakibara
S
S
D000489:Alligators and Crocodiles / Q000378:metabolism*; D000595:Amino Acid Sequence; D000803:Angiotensin I / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D003370:Coturnix; D008297:Male; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
D000804:Angiotensin II; D000803:Angiotensin I