L-(+)-Arginine

In this study, we confirmed N-terminal myristoylation of Tetrahymena pyriformis arginine kinase (AK1) by identifying a myristoylation signal sequence at the N-terminus. A sufficient amount of modified enzyme was synthesized using an insect cell-free protein synthesis system that contains all of the elements necessary for post-transcriptional modification by fatty acids. Subsequent peptide mass fingerprinting (PMF) analyses were performed after digestion with trypsin. The PMF data covered 39 % (143 residues) of internal peptides. The target N-myristoylated peptide had a theoretical mass of 832.4477 and was clearly observed with an experimental mass (m/z-H+) of 832.4747. The difference between the two masses was 0.0271, supporting the accuracy of identification and indicating that the synthesized T. pyriformis AK1 is myristoylated. The fixed specimens of T. pyriformis were reacted with an anti-AK1 peptide antibody followed by a secondary antibody with a fluorescent chromophore and were observed using immunofluorescence microscope.

The present study was carried out to find out the effect of leuprolide, a gonadotropin-releasing hormone (GnRH) receptor agonist, on l-arginine induced immunosuppression, and relates with brain and thymus levels of nitric oxide (NO). Further, the effect of leuprolide was studied in sham operated, ovariectomized and castrated mice to understand the role of sex steroids in l-arginine induced immunosuppression. Treatment with l-arginine (250, 500, 1000 mg/kg/i.p. for 7 days) increased brain and thymus levels of NO; measured by using 'NO Measuring Instrument' (Innovative Instruments Inc., USA) in dose dependent manner. It also decreased cellularity, relative weight of thymus, DNA fragmentation, humoral, and cell mediated immunity response to sheep RBC. Prior treatment of leuprolide (100μg/mouse, s.c. for 7 days) prevented l-arginine induced rise in brain and thymus tissue levels of NO as well as the changes in immunological parameters. The protective effect of leuprolide against l-arginine induced immunosuppression and rise in brain and tissue nitric oxide levels was even evident in ovariectomized and castrated mice, suggesting that the observed effect of leuprolide is independent of sex steroids, and correlated with its ability to prevent l-arginine induced rise in CNS and peripheral immune tissue levels of NO.

Reduced plasma arginine (ARG) concentrations are found in various types of cancer. ARG and its product nitric oxide (NO) are important mediators in the immune function and the defense against tumor cells. It remains unclear whether the diminished systemic ARG availability in cancer is related to insufficient endogenous ARG synthesis, negatively affecting NO synthesis, and whether a dietary amino acid mixture is able to restore this. In 13 patients with advanced non-small cell lung cancer (NSCLC) and 11 healthy controls, whole body ARG and CIT rates of appearance were measured by stable isotope methodology before and after intake of a mixture of amino acids as present in whey protein. The conversions of CIT to ARG (indicator of de novo ARG synthesis) and ARG to CIT (marker of NO synthesis), and ARG clearance (reflecting ARG disposal capacity) were calculated. Plasma isotopic enrichments and amino acid concentrations were measured by LC-MS/MS.

INTRODUCTION: Dextran sodium sulfate (DSS) is commonly used to induce a murine fulminant colitis model. Hepatocyte growth factor (HGF) has been shown to decrease the symptoms of inflammatory bowel disease (IBD) but the effect of its activator, HGFA, is not well characterized. Arginine reduces effects of oxidative stress but its effect on IBD is not well known. The primary aim is to determine whether HGF and HGFA, or arginine will decrease IBD symptoms such as pain and diarrhea in a DSS-induced fulminant colitis murine model.