Human liver molecular weight

Phosphofructokinase (PFK) is a key regulatory enzyme of glycolysis that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-diphosphate. The active PFK enzyme is a homo- or heterotetrameric enzyme with a molecular weight of 340,000. Three types of subunits, muscle type (M), liver type (L), and fibroblast (F) or platelet (P) type, exist in human tissues. Human muscle and liver PFKs consist of homotetramers (M4 and L4), whereas red blood cell PFK consists of five tetramers (M4, M3L, M2L2, ML3, and L4). Each isoform is unique with respect to affinity for the substrate fructose-6-phosphate and ATP and modulation by effectors such as citrate, ATP, cAMP, and fructose-2,6-diphosphate. M-type PFK has greater affinity for fructose-6-phosphate than the other isozymes. AMP and fructose-2,6-diphosphate facilitate fructose-6-phosphate binding mainly of L-type PFK, whereas P-type PFK has intermediate properties. 

Retention of radiocopper injected into humans is high only 10% is excreted within 72 h in urine and feces, and 50% in four weeks (Aaseth and Norseth 1986). Most (72%) of the unabsorbed copper is excreted in the feces primarily by way of the biliary duct, the salivary glands, or the intestinal mucosa a minor portion is excreted by way of sweat and menses (Schroeder et al. 1966 USEPA 1980 ATSDR 1990). In mammals, copper is excreted mainly via the bile in association with glutathione or unidentified high-molecular-weight molecules. However, the transport mechanisms of copper from liver cells into bile are essentially unknown (Aaseth and Norseth 1986). In rats, biliary excretion of copper is increased by increased flow of bile, increased body temperature, or administration of adrenal steroids (Sugawara et al. 1994). 

Nasal Administration. A route that has gained increasing popularity of late for pharmaceutical administration in humans is the intranasal route. The reasons for this popularity are the ease of use (and, therefore, ready patient acceptance and high compliance rate), the high degree and rate of absorption of many substances (reportedly for most substances up to 1000 molecular weight McMartin et al., 1987), and the avoidance of the highly acid environment in the stomach and first-pass metabolism in the liver (particularly important for some of the newer peptide moieties) (Attman and Dittmer, 1971). The only special safety concerns are the potential for irritation of the mucous membrane and the rapid distribution of administered materials to the CNS. 

The activator for the hydroly sis of G 12 catalyzed by /3-hexosaminidase A was described by Hechtman277 and Hechtman and LeBlanc.278 The GM2-specific activator was purified over 100-fold from human liver, and was identified as a heat-labile protein. This activator did not stimulate the hydrolysis of asialo-G 12 catalyzed either by hexosaminidase A or B. The molecular weight of this activator was determined to... 

Another connexin with a molecular weight of 32 kD, Cx32, was cloned from human liver [Kumar and Gilula, 1986], rat liver [Paul, 1986] and was also found in hepatocytes [Paul, 1986 Traub et ah, 1989], stomach, brain and kidney [Paul, 1986] as well as in pancreatic acinar cells [Dermietzel et ah,... 

MALDI-IMS has been employed extensively to investigate the distribution of either commercially available or prospective drugs in tissues. Troendle et al. (1999) reported using MALDI in conjunction with a quadrupole ion trap equipped with a laser microprobe to detect the dmg paclitaxel [molecular weight (MW) 853] from rat liver and human ovarian tumor tissue. The liver tissue was incubated with a solution of paclitaxel, while the ovarian tumor tissue was from an animal dosed with paclitaxel in vivo. The concentration of drug was approximately 50mg/kg in each tissue of interest. In both cases, no localization of the dmg was observed. 

Angiotensinogen is the circulating protein substrate from which renin cleaves angiotensin I. It is synthesized in the liver. Human angiotensinogen is a glycoprotein with a molecular weight of approximately 57,000. The 14 amino acids at the amino terminal of the molecule are shown in... 

Cholesteryl ester transfer protein (CETP) promotes exchange and transfer of neutral lipids such as cholesteryl ester (CE) and TG between plasma lipoproteins [63-65], The function of CETP is illustrated in Fig. 3. CETP is a very hydrophobic and heat-stable glycoprotein with an apparent molecular weight of 74 kDa as determined by SDS-PAGE analysis [66,67], The cDNA from human liver was cloned and sequenced [68], It encodes for a 476-amino acid protein (53 kDa), suggesting that the apparent higher molecular weight is due to the addition of carbohydrate residues by posttranslational modification. 

Nevertheless, reliable methods using the SIM mode were introduced for TA analysis. The SIM mode was used for analysis of atropine and scopolamine from human viscera [15] and human plasma [11] (Table 8), of tropisetron from liver microsomal incubation mixtures [82] (Table 7), of granisetron from rat plasma [72], of hyoscyamine enantiomers from human plasma [48], of scopolamine from rabbit plasma [89], of tiotropium from human plasma [81] (Table 5) and of atropine from dog plasma [96] (Table 6). The corresponding values for the monoisotopic molecular weight (MW) and the corresponding m/z-val ucs of protonated TTA and pure QTA are summarized in Table 9. 

Aldehyde reductase from human liver catalyses attack by the 4-pro-R hydrogen on the Re face of the carbonyl [135]. 4-Nitrobenzaldehyde and 3,4-dihydroxyphenylglycolaldehyde are good substrates [135,136]. This enzyme is monomeric with molecular weight 36000 [137]. Pig kidney [138] and pig liver [139] also contain a monomeric aldehyde reductase that catalyses Re attack by the 4-pro-R hydrogen, and has molecular weight around 35000. Several other tissues and species contain closely similar enzymes [140-142]. 

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