Biochemistry
Parinaz Hajiyousefipour; Mehdi Basaki; Davoud Kianifard; Yousef Panahi; Mehri Anisi
Abstract
Nicotine is a natural alkaloid and the primary cause of tobacco addiction. Nicotine stimulates the brain, raises blood pressure and heart rate, increases metabolic rate, suppresses appetite, and regulates body weight through binding to nicotinic acetylcholine receptors (nAChRs). Nicotine causes weight ...
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Nicotine is a natural alkaloid and the primary cause of tobacco addiction. Nicotine stimulates the brain, raises blood pressure and heart rate, increases metabolic rate, suppresses appetite, and regulates body weight through binding to nicotinic acetylcholine receptors (nAChRs). Nicotine causes weight loss, enzyme leakage, lipid peroxidation, and oxidative stress in the liver. To investigate the time-dependent effects of nicotine on liver function rats were injected intraperitoneally daily with of nicotine (2 mg/kg). Forty blood samples were taken at four stages, as four independent groups, before nicotine administration and 30 minutes, one week, and four weeks after the first nicotine administration. Serum glucose, albumin, urea, and uric acid were measured by standard methods. After four weeks of nicotine administration, liver samples were fixed in a 10% formaldehyde solution, and diameters of the central vein, hepatocyte, and sinusoid and thickness of the liver capsule were measured. Short and long-term nicotine administration decreased serum glucose and albumin. Serum urea and uric acid decreased following immediate, short-term, and long-term nicotine administration. Also, the diameter of hepatocytes and sinusoids increased after four weeks of nicotine administration. Nicotine reduces hepatic synthesis of glucose, albumin, urea, and uric acid time-dependently through various regulatory mechanisms. Investigating nicotine's effects on the genes and enzymes involved in liver metabolism will help to clarify the molecular mechanisms of nicotine's effects.
M. Kouhiyan; B. Shareghi; F. Kouhiyan
Volume 1, Issue 1 , October 2012, , Pages 24-30
Abstract
Pepsin (E.C.3.4.23.1) is a juice gastric aspartic proteinase. It belongs to hydrolyses family. Its monomeris structure is consisting of two lobes that they are similar in size and folding. It consists of a single polypeptide chain of molecular weight 34644 Daltone and 327 aminoacid. Structural analysis ...
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Pepsin (E.C.3.4.23.1) is a juice gastric aspartic proteinase. It belongs to hydrolyses family. Its monomeris structure is consisting of two lobes that they are similar in size and folding. It consists of a single polypeptide chain of molecular weight 34644 Daltone and 327 aminoacid. Structural analysis shows that pepsin contains 1.2% basic residues, 13.1% acidic residues, 46.5% polar residues and 39.2% hydrophobic residues. Structural stability of pepsin was investigated by UV-VIS spectrophotometer and spectrophlorimetry. Spectral measurements were made by sodium phosphate buffer .02M at pH: 2 and temperatures between 30 and 100 º C. It was observed that (1) high considerable enzyme stability, (2) enzyme stability decreases in the presence of urea at pH: 2. (3) thermodynamic parameters decline in the presence of urea. (4) Florescence intensity increase in the presence of urea.
