Aminopeptidase was detected in homogenates of the free-living nematode Panagrellus redivivus with the aminoacyl substrate L-alanine-4-nitroanilide. Subcellular distribution of activity was 80% soluble and 20% membrane-associated. Aminopeptidases in the two fractions differed in affinity for Ala-4-NA, with Km's of 0.65 mM (soluble) and 2.90 mM (membrane). Specific activities (units/mg) at pH 7.8...

Temperature affects all biological functions and will therefore modulate ecologically significant interactions between animals and their environment. Here, we examined the effect of ambient temperature (Ta) on the thermal biology and energy budget in striped hamsters acclimated to cold (5°C), warm (21°C) and hot temperatures (31°C). Thermoneutral zone (TNZ) was 22.5-32.5°C, 25-32.5°C and 30-32....

Proteolytic removal of the pre-segment from growing nascent chains of pre-human placental lactogen (hPL) occurred during in vitro translation of placental mRNA if crude membranes derived from ascites lysates, dog pancreas, or rat liver rough endoplasmic reticulum were added to the translation mixtures. The cotranslational proteolytic event was inhibited by the peptide protease inhibitor, chymos...

The insulin-responsive glucose transporter GLUT4 is targeted to a post-endocytic compartment in adipocytes, from where it moves to the cell surface in response to insulin. Previous studies have identified two cytosolic targeting motifs that regulate the intracellular sequestration of this protein: FQQI(5-8) in the N-terminus and LL(489,490) (one-letter amino acid notation) in the C-terminus. In...

Peptides representing single repeat units of the carboxy-terminal domain (CTD) of RNA polymerase II (Tyr-Ser-Pro-Thr-Ser-Pro-Ser-Tyr-NH2, 1) contain overlapping Ser-Pro-Xaa-Xaa beta-turn forming sites which permit their overall structure to closely resemble members of the quinoxaline class of antitumor DNA bisintercalators. We have modified this native sequence at the i+2 positions of each beta...

The preferred ligand of angiotensin (Ang) II type 2 (AT(2)R)-mediated natriuresis is Ang III. The major enzyme responsible for the metabolism of Ang III is aminopeptidase N, which is selectively inhibited by compound PC-18. In this study, urine sodium excretion rates (U(Na)V), fractional excretion of sodium, fractional excretion of lithium, glomerular filtration rate, and mean arterial pressure...

Almost all naturally occurring metalloproteases are monozinc enzymes. The zinc in any number of zinc metalloproteases has been substituted by some other divalent cation. Almost all Co(II)- or Mn(II)-substituted enzymes maintain the catalytic activity of their zinc counterparts. However, in the case of Cu(II) substitution of zinc proteases, a great number of enzymes are not active, for example, ...

The binding of F4+ enterotoxigenic Escherichia coli (ETEC) and the specific receptor on porcine intestinal epithelial cells is the initial step in F4+ ETEC infection. Porcine aminopeptidase N (APN) is a newly discovered receptor for F4 fimbriae that binds directly to FaeG adhesin, which is the major subunit of the F4 fimbriae variants F4ab, F4ac, and F4ad. We used overlapping peptide assays to ...

The mechanism of hydrolysis and absorption of a proline-containing tetrapeptide, Leu-Pro-Gly-Gly (10 mM) by rat intestine was examined in vivo by using jejunal perfusion methods. The peptide substrate and hydrolysis products were analyzed by use of an automated amino acid analyzer. Leucine, proline, and glycine were absorbed by the intestine at a significantly higher rate from the tetrapeptide ...

Insecticidal crystal proteins of Bacillus thuringiensis bind to receptors in the midgut of susceptible insects leading to pore formation and death of the insect. The identity of the receptor is not clearly established. Recently a direct interaction between a cloned and heterologously expressed aminopeptidase (slapn) from Spodoptera litura and the Cry1C protein was demonstrated by immunofluoresc...