To elucidate the physiological and pathophysiological significance of methionine- and leucine-enkephalin (Met-and Leu-enkephalin, respectively) in human sympathoadrenal system, the contents of these peptides in normal human sympathetic nervous system, adrenal medulla, and pheochromocytomas were determined by specific radioimmunoassays combined with reverse-phase high-performance liquid chromato...

1. The cardiovascular effects of enkephalins have been tested in normotensive Wistar-Kyoto rats. Methionine-enkephalin and leucine-enkephalin increased blood pressure and heart rate after infusion into the brain ventricles. 2. After intravenous injection, blood pressure was increased by methionine-enkephalin and leucine-enkephalin, but heart rate was increased by methionine-enkephalin only. 3. ...

A specific carboxypeptidase that converts enkephalin precursors into enkephalin in adrenal chromaffin granules has been purified and characterized. In the adrenal this enzyme, designated enkephalin convertase, is uniquely localized to the chromaffin granules, which contain enkephalin and precursor peptides. Enkephalin convertase is markedly stimulated by CoCl2 and inhibited by EDTA or 1,10-phen...

Endogenous [5-methionine]enkephalin (Metenkephalin) and [5-leucine]enkephalin (Leu-enkephalin) are released from perfused slices of rat globus pallidus by increased K(+) in a Ca(2+)-dependent manner. Tissue perfused for 40 min contained only 26% of the Met-enkephalin and 44% of the Leu-enkephalin found in the freshly dissected tissue. After perfusion, the mean (+/-SEM) ratio (wt/wt) of Met-enke...

Intracellular records were made from neurones in the submucous plexus of the guinea-pig caecum. [Met5]enkephalin, [Leu5]enkephalin, [D-Ala2,D-Leu5]enkephalin (DADLE) and [D-Ser2,Leu5]enkephalin-Thr (DSLET) hyperpolarized the membrane when applied in concentrations of 30 nm-10 microM. Normorphine, [D-Ala2, MePhe4,Gly5]enkephalin-ol (DAGO), [D-Ala2,MePhe4,Met(0)5]enkephalin-ol (FK33824), dynorphi...

[Met]Enkephalin-Arg6-Phe7 is an opiate-like peptide normally found in the the adrenal gland and brain that has analgesic (antinociceptive) activity when administered directly into the cerebral ventricles of mice. On a molar basis, [Met]-enkephalin-Arg6-Phe7, with a median effective dose (ED50) of 38.5 nmol/mouse, is 8 times more potent than [Met]enkephalin. As with [Met]enkephalin, analgesic ac...

In order to assess the individual effects of each of the 3-methyl groups in residue 2 of [D-Pen2, D-Pen5]enkephalin on binding affinity to mu and delta opioid receptors, (2S,3S)methylcysteine ((3S)Me-D-Cys) and (2S,3R)methylcysteine ((3R)Me-D-Cys) were synthesized and incorporated into the analogs, [(3S)Me-D-Cys2, D-Pen5] enkephalin and [(3R)Me-D-Cys2, D-Pen5]enkephalin. Of these analogs, [(3S)...

A 3200-dalton adrenal enkephalin-containing peptide, designated peptide E, that exhibits high opiate activity in the guinea pig ileum longitudinal muscle preparation was purified, and its structure was determined. It contains an amino-terminal [Met]enkephalin sequence and a [Leu]enkephalin sequence at the carboxyl terminus. Sequence analysis revealed that peptide E arises from a previously char...

Abstract VUV action spectroscopy has recently gained interest for the study of peptides and proteins. However, numerous aspects fundamental processes involved in photodissociation are yet to be understood. It can, example, expected that sulfur-containing amino-acid residues have a significant impact on dissociation following photoionization because their potential involvement transport electron...