Biomedical subjects

T X Watanabe

Publications and source records attributed to T X Watanabe.

At least 19 recordsLinked to original sources

PubMed1999

Teleost-type angiotensin is present in Australian lungfish, Neoceratodus forsteri.

Angiotensin I (ANG I) was produced from the incubation of lungfish plasma with homologous kidney extracts. The purified peptide was found to have the sequence of H-Asn-Arg-Val-Tyr-Val-His-Pro-Phe-Thr-Leu-OH, which is homologous for the first eight residues with all teleost angiotensins so far sequenced, although lungfish generally possess tetrapod-type hormones. The lungfish decapeptide (ANG I) induced dose-dependent increases in arterial pressure in the rat. The lungfish octapeptide (ANG II) released aldosterone from kidney-adrenal tissue in vitro in a dose-dependent manner and induced dose-dependent increases in arterial pressure of the lungfish. Substitution of asparagine with aspartic acid in the first position (tetrapod-type ANG II) did not alter the blood pressure response significantly, but a second substitution of the valine in the (5)-position with isoleucine (ANG II form found in human and rat) abolished the rise in arterial pressure in lungfish over the same dose range.

Angiotensin I↗

PubMed1999

The chimeric peptide [Lys(-2)-Arg(-1)]-sarafotoxin-S6b, composed of the endothelin pro-sequence and sarafotoxin, retains the salt-bridge staple between Arg(-1) and Asp8 previously observed in [Lys(-2)-Arg(-1)]-endothelin. Implications of this salt-bridge in the contractile activity and the oxidative folding reaction.

The chimeric peptide [Lys(-2)-Arg(-1)]-sarafotoxin-S6b (KR-SRTb) designed from the Lys-2-Arg-1 dipeptide of the endothelin pro-sequence and the sarafotoxin-S6b sequence was synthesized. Its contractile activity was found to be decreased markedly when compared with that of the parent SRTb. In contrast, the extension by the Lys-Arg dipeptide was found to increase the formation of the native disulfide isomer (82/18 versus 96/4) when the reaction was carried out in the presence of redox reagents. The solution structure of KR-SRTb was determined by NMR as a function of pH. In the carboxylic acid state, the structure consists of the cystine-stabilized alpha-helical motif, with the alpha-helical part spanning residues 9-15, and of an unstructured C-terminal tail. In the carboxylate state, the structure is characterized by a salt-bridge between Arg(-1) and Asp8, which we identified previously in the [Lys(-2)-Arg(-1)]-endothelin-1 peptide (KR-ET-1). The fact that this salt-bridge is commonly observed in KR-SRTb and KR-ET-1, despite the 33% sequence difference between the corresponding parental peptides, highlights the remarkable adaptability of the Lys-Arg extension for the formation of a special salt-bridge. As a consequence, this salt-bridge, which does not depend on either the 4-7 sequence of the loop or the C-terminal sequence, appears to be particularly well suited to improve the stability of the cystine-stabilized alpha-helical motif. Therefore, because of its high yield in the native disulfide arrangement and its high permissiveness for sequence mutation in the 4-7 loop, such a stabilized cystine-stabilized alpha-helical motif could be a valuable scaffold for the presentation of a library of constrained short peptides.

Amino Acid Sequence↗

PubMed1998

Isomorphous replacement of cystine with selenocystine in endothelin: oxidative refolding, biological and conformational properties of [Sec3,Sec11,Nle7]-endothelin-1.

Air re-oxidation of fully reduced human endothelin-1 under optimized conditions yields the natural isomer with parallel disulfide bridges and the non-natural isomer with crossed disulfide bridges at a ratio of 3:1. In view of the recently determined highly reducing redox potential of selenocysteine (-381 mV) in peptides, the half-cystine residues Cys3 and Cys11 of the natural isomer of endothelin-1 were replaced by selenocysteine. Taking advantage of the high stability of the diselenide group toward reducing agents for disulfides a regioselective disulfide bridging of the second cysteine pair allowed for straightforward preparation of the [Sec3,Sec11, Nle7]-endothelin-1. NMR structural analysis showed conformational preferences of this endothelin analog that were identical to those of the natural hormone. Similarly, the bioactivity data confirmed that replacement of cysteine residues with selenocysteine was without detectable effect on receptor recognition and signal transduction. Both findings strongly support that the exchange of sulfur against selenium produces a fully isomorphous molecule as recently observed for similar exchanges at the level of methionine residues in proteins. Moreover, oxidative refolding of the fully reduced [Sec3,Sec11,Nle7]-endothelin-1 fulfilled the expectation that the redox potential of the selenocysteines would dictate quantitative formation of the natural isomer. These results suggest that the selenocysteine approach, besides offering an interesting chemical tool for induction of correct oxidative folding of multiple cysteine-containing peptides, should even allow for the preparation of non-natural isomers and thus for studying conformational preferences of folding intermediates in peptides and proteins.

Amino Acid Sequence↗

PubMed1998

Tetrapod-type [Asp1] angiotensin is present in a holostean fish, Amia calva.

The renin-angiotensin system has been identified in various vertebrates, from elasmobranchs to mammals. Tetrapod (amphibians to mammals) angiotensin (ANG) has Asp at the N-terminus, but Asp is replaced by Asn in elasmobranch and teleost fish. ANG I has been isolated from incubates of plasma and kidney extracts of the bowfin Amia calva, a holostean fish, using the eel vasopressor activity as an assay system; its sequence was found to be H-Asp-Arg-Val-Tyr-Val-His-Pro-Phe-Asn-Leu-OH after sequence analysis, mass spectrometry, and comparison with the synthetic peptide. This sequence is identical to bullfrog ANG I. [Asn1] ANG I was not detected. Thus the bowfin is the first fish species which contains only [Asp1] ANG I. The bowfin ANG I and II were no more vasopressor than eel peptides in the bowfin, indicating that bowfin ANG II receptors do not distinguish between [Asp1] and [Asn1] peptides. In the rat, bowfin ANG I and rat [Ile5, His9] ANG I have equipressor activities when examined in different animals, but the vasopressor activity of bowfin ANG I decreased following rat ANG I in the same animals, although the activity of rat ANG I was unaffected after bowfin ANG I. The present study directly demonstrates the presence of the renin-angiotensin system in a holostean fish and showed that its ANG II receptors have not yet fully coevolved with the homologous [Asp1] peptide.

Angiotensin I↗

PubMed1997

A new natriuretic peptide isolated from cardiac atria of trout, Oncorhynchus mykiss.

Atrial and brain natriuretic peptides (ANP and BNP, respectively) are two cardiac natriuretic peptides (NPs) found in tetrapods from amphibians to mammals, whereas ANP and ventricular NP (VNP) have been identified in eel hearts. Because VNP has also been found in the rainbow trout ventricle, we attempted to isolate NP from trout cardiac atria in order to determine whether ANP and VNP are common cardiac NPs in teleosts. In the present experiments, we isolated VNP and a novel atrial NP consisting of 29 amino acid residues from the atria. This new trout NP exhibited similar sequence identity to mammalian ANP and BNP (50-60%). Its homology to eel ANP was low (52%) compared with high homology of trout and eel VNP (78%). Based on yield, the content of this new NP in trout atria may be even smaller than that of VNP. The new trout atrial NP exhibited low relaxant activity in the chick rectum (only 1/10 of that of trout VNP), and extremely low vasorelaxant activity in the rat aortic strip (only 1/400 of that of human ANP). However, the new trout NP was equipotent with trout VNP and human ANP in relaxing trout epibranchial artery. Based on the sequence similarity with other NPs and on atrial content, the new NP isolated from trout atria cannot yet be assigned to a known member of the NP family.

Amino Acid Sequence↗

PubMed1997

Primary structure and bioactivity of bullfrog calcitonin.

Calcitonin was isolated from the bullfrog, Rana catesbeiana, and the first amino acid sequence of an amphibian calcitonin was determined to be Cys-Ser-Gly-Leu-Ser-Thr-Cys-Ala-Leu-Met-Lys-Leu-Ser-Gln-Asp-Leu-His- Arg-Phe-Asn-Ser-Tyr-Pro-Arg-Thr-Asn-Val-Gly-Ala-Gly-Thr-Pro-NH2. Some portions of this sequence are specific to bullfrog calcitonin, and other portions are similar both to teleost calcitonins and to mammalian calcitonins. Administration of 5 pmol of bullfrog calcitonin to rats revealed a hypocalcemic potency similar to that of salmon calcitonin, at least for the first 3 hr.

Amino Acid Sequence↗

PubMed1997

Effects of homologous atrial, brain, and C-type natriuretic peptides on isolated heart and blood vessels of bullfrog.

The cardiovascular effects of homologous natriuretic peptides (fNPs) were examined in the bullfrog, Rana catesbeiana. Synthetic bullfrog atrial natriuretic (fANP), brain natriuretic (fBNP) and C-type natriuretic peptides (fCNP I and fCNP II), were tested in vitro and compared under the same experimental conditions. All frog NPs produced a significant, and concentration-dependent, reduction in tension (relaxant effect) in the isolated dorsal aorta. Frog CNP II exhibited similar vasorelaxation profile as that of fANP, while fBNP and fCNP I had lower activity than fANP. Frog NPs inhibited norepinephrine induced contraction and fCNP II was most potent. In isolated preparations of atrium and ventricle, fCNP I and II produced a significant, and concentration-dependent, reduction in tension, but neither fANP nor fBNP produced any significant effects. Frog CNP II is most potent among fNPs in relation to reduce the cardiac output. Chronotropic responses of the heart to administrations of NPs were insignificant. The present results for the first time showed that fNPs play roles in the control of cardiovascular system, both blood vessels and heart, in the bullfrog.

Animals↗

PubMed1996

B-type natriuretic peptide isolated from frog cardiac ventricles.

A new natriuretic peptide with 27 amino acid residues has been isolated from cardiac ventricles of the bullfrog, Rana catesbeiana. Since this ventricular peptide had high sequence identity to B-type (brain) natriuretic peptide (BNP), especially to chicken BNP (74%), we named it bullfrog BNP. Thus, semi-aquatic amphibians have tetrapod-type BNP, but do not seem to have fish-type ventricular natriuretic peptide (VNP) in their ventricles. Compared with other known BNPs, the C-terminus of bullfrog BNP was elongated by two amino acid residues and was not amidated. Bullfrog BNP dose-dependently decreased arterial blood pressure in the bullfrog with a potency twofold greater than that of human ANP. Bullfrog BNP also exhibited vasodepressor, natriuretic and diuretic activities in the rat, but it was 1/3, 1/7, and 1/17 as potent as human ANP in this mammalian species.

Amino Acid Sequence↗

PubMed1996

Vasopressor activities of N-terminal fragments of adrenomedullin in anesthetized rat.

Adrenomedullin (AM) is a vasorelaxant peptide that was recently isolated from human pheochromocytoma. In contrast to human (h) AM, which has vasodepressor activity, a synthetic N-terminal fragment of hAM, hAM-(1-25)-NH2 showed vasopressor activity in the anesthetized rat. The N-terminal peptides hAM-1-31)-NH2, hAM-(1-25)-OH, hAM-(1-21)-NH2, acetyl-hAM-(16-21)-NH2, and acetyl-hAM-(16-36)-OH all showed vasopressor activities. The potency of hAM-(1-21)-NH2, acetyl-hAM-(16-21)-NH2 was greater than that of hAM-(1-25)-NH2. Pretreatment with phenoxybenzamine, guanethidine, or reserpine attenuated vasopressor activities of these peptides. These data suggested that vasopressor activity of N-terminal fragment of hAM is due to a stimulation of endogenous catecholamine release.

Adrenal Gland Neoplasms↗

PubMed1996

Effects of calciseptine on unitary barium channel currents in guinea-pig portal vein.

Effects of synthesized calciseptine (CaS), found naturally in the venom of the black mamba, on voltage-dependent Ca2+ channels in smooth muscle cells of the guinea-pig portal vein were investigated. In the whole-cell voltage-clamp configuration, extracellular application of CaS (>/= 10 nM) inhibited the inward current in a concentration- and voltage-dependent manner at a holding potential of -90 mV. The Ca2+ current recorded at a high holding potential (-50 mV) was approximately 8 times more sensitive to CaS than that at a more negative holding potential (-90 mV). CaS (50 nM) shifted to the left the steady-state inactivation curve obtained by using single 8-s conditioning pulses of various amplitudes. When CaS (>/= 200 nM) was present in the pipette, the Ca2+ current remained for the duration of the experiments (more than 60 min) in the whole-cell configuration. Two different Ca2+ channel conductances are present in this tissue (25-pS and 12-pS channels). Both channels are blocked by dihydropyridine (DHP) derivatives, but have different sensitivities. In the cell-attached condition, CaS hardly changed the activity of either unitary Ca2+ channel current. To prevent the "run down" of the Ca2+ channels in cell-free conditions, we added cardiac cytosol, a supernatant from homogenized cardiac cells and an endogenous Ca2+ channel activating factor, in the pipette. The unitary Ca2+ channel currents were then recorded using the outside-out membrane patch configuration. Application of CaS (1 microM) in the bath completely blocked the open events of the 25-pS Ca2+ channel. CaS (10 nM) in the bath reduced the mean open time and channel availability, resulting in a decrease in the open probability of the 25-pS channel currents without affecting the amplitude of the single-channel conductance. CaS also reduced the open probability (though less potently) and channel availability of the 12-pS Ca2+ channel without a change in its amplitude. From these results, we conclude that CaS has inhibitory effects on the voltage-dependent Ca2+ current that are similar to those of DHP derivatives and that it acts from the outside of the membrane.

Animals↗

PubMed1995

Smooth muscle relaxing and hypotensive activities of synthetic calciseptine and the homologous snake venom peptide FS2.

The biological activities of synthetic calciseptine and FS2, a homologous peptide from snake venom, were determined using in vitro and in vivo preparations. Calciseptine and FS2 produced dose-dependent relaxation in pre-constricted rat aorta, pulmonary artery and trachea. The onset and duration pattern of these relaxing effects were similar to those caused by nifedipine, an L-type Ca2+ channel blocker. Calciseptine relaxed the contraction of rat aorta provoked by an L-type channel agonist, Bay K 8644. This relaxation was not affected by NG-nitro-L-arginine, indomethacin or propranolol. Calciseptine and FS2 inhibited the contraction caused by acetylcholine in guinea pig ileal longitudinal muscle. In case of in vivo study using anesthetized rats, calciseptine, FS2 and nifedipine showed depressor effects. The hypotensive effects of the two peptides were more potent and sustained than that of nifedipine. These findings show that both synthetic calciseptine and FS2 have similar biological activities like nifedipine, an L-type Ca2+ channel blocker. In addition, these two peptides with large molecular weights may be unique and useful tools for studying the Ca2+ channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1994

Specific receptors for adrenomedullin in cultured rat vascular smooth muscle cells.

The effects of synthetic rat adrenomedullin (rAM), a novel vasorelaxant peptide originally isolated from human pheochromocytoma, on receptor binding and cAMP generation were studied in cultured rat vascular smooth muscle cells (VSMC). A binding study using [125I]rAM revealed the presence of a single class of high-affinity (Kd 1.3 x 10(-8) M) binding sites for rAM in VSMC. The apparent Ki of rat calcitonin gene-related peptide (rCGRP) was 3 x 10(-7) M. Affinity labeling of VSMC membranes with [125I]rAM revealed two distinct labeled bands with apparent molecular weights of 120 and 70 kDa, both of which were abolished by excess unlabeled rAM or rCGRP, rAM stimulated cAMP formation with an approximate EC50 of 10(-8) M, the effect of which was additive with isoproterenol, but not with rCGRP. The rAM-induced cAMP response was unaffected by propranolol, indomethacin, or quinacrine, but inhibited by a CGRP receptor antagonist, human CGRP[8-37]. These data suggest that VSMC possesses specific AM receptors functionally coupled to adenylate cyclase with which CGRP interacts.

Adrenomedullin↗

PubMed1994

Rainbow trout ventricular natriuretic peptide: isolation, sequencing, and determination of biological activity.

Ventricular natriuretic peptide (VNP) is a new type of cardiac natriuretic peptide initially isolated from the eel ventricle. VNP has been isolated from cardiac ventricles of the rainbow trout, Oncorhynchus mykiss, and found to consist of 35 amino acid residues carrying a C-terminal tail sequence with 14 amino acid residues. Thus, the long C-terminal sequence characteristic of VNP was also conserved in the trout VNP. A VNP with 4 amino acid residues truncated from the C-terminus was also isolated from trout ventricles and sequenced. Sequence identity of trout VNP to eel VNP was 77%; while it was 56% to eel A-type natriuretic peptide (ANP). Trout VNP caused characteristic biphasic vasopressor/depressor effects in the trout similar to those produced by rat and eel ANP. Trout VNP and human ANP were almost equipotent in their vasopressor and depressor activity in trout. Unlike eel VNP, therefore, homologous VNP did not exhibit greater activity in the trout. In the rat, however, trout VNP was more potent than eel peptide and was almost equipotent to human ANP for both vasodepressor and natriuretic effects. The high potency of trout VNP appears to be due in part to its longer-lasting effect compared to human ANP.

Amino Acid Sequence↗

PubMed1994

Centrally induced vasopressor and sympathetic responses to a novel endogenous peptide, adrenomedullin, in anesthetized rats.

Possible central actions of adrenomedullin were explored and compared with the peripheral effects by injecting it into the lateral ventricle, cisterna magna, and femoral vein in urethane-anesthetized rats. Adrenomedullin, 1.0 to 3.0 nmol/kg, injected intravenously (i.v.), caused a transient vasodepression of about 10 to 30 mm Hg, dose dependently, which lasted for < 15 min. On the other hand, intracerebroventricular (ICV) and intracisternal (IC) injections of adrenomedullin elicited sustained elevations of arterial pressure of gradual onset, dose dependently; the arterial pressure started to rise at about 3 min after the injection, and gained peak response after > 20 min. The pressor response lasted for > 2 h. Heart rate was not significantly influenced by these doses of adrenomedullin. The abdominal sympathetic outflow was markedly increased in relation to the blood pressure elevation. The time-course of the responses was quite similar with both ICV and IC injections. Hypotensive effects of i.v. injected adrenomedullin was partially attenuated, and the centrally induced vasopressor responses were abolished by the pretreatment with human calcitonin gene-related peptide (hCGRP)-receptor antagonist, hCGRP(8-37). These findings indicate that the receptors for adrenomedullin exist in the brain, and that the receptor site may be anatomically far from the surface of the brain and the ventricular system because the onset of the pressor response was delayed. Or, CGRP and adrenomedullin may share the same receptors, particularly in the brain.

Adrenomedullin↗

PubMed1994

Pre-B cells adhere to fibronectin via interactions of integrin alpha 5/alpha V with RGDS as well as of integrin alpha 4 with two distinct V region sequences at its different binding sites.

The present study aimed to develop an assay system capable of directly examining the adhesion of cells to each cell-binding site on fibronectin (FN) and to investigate molecular mechanisms underlying the pre-B cell-FN interaction. Treatment of culture plates with 3-(2-pyridyldithio) propionic acid N-hydroxysuccinimide ester and subsequently with dithiothreitol (DTT) allowed the plates to adsorb DTT-treated extracellular matrix (ECM) proteins as well as synthetic peptides containing cysteine at the N-terminal. These treatments produced culture plates coated with ECM proteins or peptides corresponding to its cell-binding sequences, i.e. three sites on FN termed RGDS, LDVP, and RGDV. Pre-B cells exhibited potent adhesiveness to FN-coated plates. Its FN binding was most efficiently inhibited by adding a combination of free forms of RGDS, LDVP, and RGDV peptides, indicating the involvement of these three cell-binding sites in the pre-B cell-FN interaction. In accordance with this, pre-B cells exhibited considerable and potent binding to the respective RGDS-, LDVP-, or RGDV-coated plates. Such binding was specific for the peptide used for coating, because each binding to a given peptide-coated plate was inhibited only by addition of a homologous free peptide. This assay system further demonstrated that the pre-B cell binding to RGDS was mediated by the alpha 5 and alpha v integrins, whereas the binding to LDVP and RGDV was mediated by the alpha 4 integrin. It was also shown that LDVP binding was inhibited by LDVP but not by RGDV and, likewise, RGDV binding was inhibited by RGDV but not by LDVP.2+ interaction involving complex molecular mechanisms.

Amino Acid Sequence↗

PubMed1994

Structure-activity relationship of adrenomedullin, a novel vasodilatory peptide, in cultured rat vascular smooth muscle cells.

Vascular smooth muscle cells (VSMC) from rat aorta possess specific receptors for a novel potent vasorelaxant peptide, adrenomedullin (AM). To elucidate its receptor coupling to guanine nucleotide-binding stimulatory protein and the structural requirement of the AM molecule to its vascular receptors, we have studied the effects of guanine nucleotides on [125I]human (h) AM binding and adenylate cyclase activity in cultured rat VSMC, and the effects of various synthetic hAM analogs on [125I]hAM binding and the cAMP response. Guanosine 5'-O-(3-thiotriphosphate) dose dependently inhibited [125I]hAM binding to rat VSMC membranes. hAM stimulated adenylate cyclase activity, and its effect was additive with GTP. hAM-induced cAMP formation was abrogated by pretreatment with cholera toxin, but not by that with pertussis toxin. Intact hAM-(1-52)-NH2 and N-terminal truncated derivatives [hAM-(13-52)-NH2, hAM-(16-52)-NH2] almost equally inhibited [125I]hAM binding and stimulated cAMP formation, whereas removal of C-terminal Tyr52 residue [hAM-(1-51)-NH2] remarkably decreased receptor-binding activity and the cAMP response. The effects of hAM-(1-52)-OH, hAM-(1-51)-OH, and a linear hAM analog ([carbamoylmethyl-Cys16,21]hAM-NH2) were far less potent on receptor binding and the cAMP response than that of hAM-(1-52)-NH2. The C-terminal fragment [hAM-(33-52)-NH2] and the N-terminal fragment [hAM-(1-10)-OH] had neither receptor-binding nor adenylate cyclase activity. hAM-(22-52)-NH2 had no agonistic effect, but showed an antagonistic effect on the hAM-induced cAMP response. These data suggest that vascular AM receptors are functionally coupled to adenylate cyclase via guanine nucleotide-binding stimulatory protein. Studies of the structure-activity relationship of hAM revealed that the cyclic structure formed by the disulfide bridge and amidation of the C-terminal residue of the AM molecule are critical for receptor binding and subsequent cAMP generation and suggest that the C-terminal fragment hAM-(22-52)-NH2 may be an antagonist for vascular AM receptors.

Adenylate Cyclase Toxin↗

PubMed1994

Eel ventricular natriuretic peptide: isolation of a low molecular size form and characterization of plasma form by homologous radioimmunoassay.

Ventricular natriuretic peptide (VNP) with 25 amino acid residues was isolated from the low molecular weight fraction of acid extracts of eel cardiac ventricles. No other short forms of VNP were recovered from the fraction. This peptide was named eel VNP(1-25) because it was a C-terminally truncated form of the previously isolated eel VNP(1-36). As observed before with eel VNP(1-36), eel VNP(1-25) had a much higher (146-fold) vasodepressor activity than human atrial natriuretic peptide (ANP) in eels, but was a third to a half as active in rats with respect to vasodepressor and natriuretic activities. Eel VNP(1-25) was generally less potent than eel VNP(1-36) for vasodepressor and natriuretic effects. A specific radioimmunoassay (RIA) has been developed for the measurement of eel VNP. The antiserum, raised against eel VNP(1-36), was highly specific and did not exhibit significant cross-reactivity with eel ANP and C-type natriuretic peptide, even though their amino acid sequences have more than 60% homology with that of eel VNP. The sensitivity of assay was 0.5 fmol/tube for eel VNP(1-36) with more than 99% confidence. Such high sensitivity permitted direct assaying of VNP with only a few microliters of plasma. In fresh water eels, the concentration of VNP in the cardiac ventricle was higher than those in the atrium or brain and that of ANP in the ventricle. Thus, VNP seems to be a ventricular hormone. Although ANP is a major circulating hormone in mammals, the plasma concentration of VNP was threefold higher than that of ANP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Amino acid sequence of sardine calcitonin and its hypocalcemic activity in rats.

A novel calcitonin (CT) was isolated from the spotlined sardine, Sardinops melanostictus. The primary structure of sardine CT was determined as follows: H-Cys-Ser-Asn-Leu-Ser-Thr- Cys-Ala-Leu-Gly-Lys-Leu-Ser-Gln-Glu-Leu-His-Lys-Leu-Gln-Ser-Tyr-Pro-Arg- Thr- Asn-Val-Gly-Ala-Gly-Thr-Pro-NH2. This amino acid sequence was different from that of salmon CT in 4 amino acid residues at positions 8th, 21th, 27th and 29th. As judged by the international method of CT bioassay, hypocalcemic activity of sardine CT was calculated as 4156 IU/mg. When compared for durability of CTs, it was found that sardine CT was significantly more potent than that of salmon CT. This is the first report of CT from a marine species of teleost.

Amino Acid Sequence↗