Leucine serum

Similarly, chemical hydrolysis of a number of a-amino acyl prodrugs of metronidazole (8.100, R=H see Sect. 8.5.4) was compared to the serum-catalyzed reaction [135][136]. The amino acids used for esterification included alanine, glycine, isoleucine, leucine, lysine, phenylalanine, and valine. Under physiological conditions of pH and temperature, ty2 values for hydrolysis in human serum ranged from 4.5 min for the Phe ester to 96 h for the lie ester. A good linear relationship was established between the log of the rate constant of enzymatic hydrolysis and the log of the rate constant of HO-cata-... 

Enzymes activities are particularly sensitive to the anticoagulant used in collecting the specimen. Heparin inhibits acid phosphatase (W16) and muramidase (Z5). Amylase activity is inhibited by oxalate or citrate (MIO), and lactic dehydrogenase and acid phosphatase lose activity in oxalate (C2). Alkaline phosphatase is stable in oxalate, oxalate-fluoride, or heparin, but 25 mAf citrate inhibits 50% of the activity, and as little as 50 mlf EDTA is completely inhibitory (B19). Leucine aminopeptidase is inhibited by EDTA, as is creatine phosphokinase (F3). Amylase activity has been reported to be only 83% of that in serum when oxalate or citrate-plasma is used (MIO). Heparin plasma appears to have no inhibitory effect. Despite the fact that clotting factor V is not stable in oxalate or EDTA, these are often used as anticoagulants to obtain plasma for prothrombin determinations (Z2, Z4). 

Our laboratory started to work on circadian rhythms by serendipity, while studying the liver-specific transcription of the serum albumin gene. We isolated a cDN A copy for a transcription factor that we dubbed DBP (for albumin promoter D-element Binding Protein). DBP, a basic leucine zipper (bZip) transcription factor, is the founding member of the PAR (proline-acidic amino acid rich)-domain bZip transcription factors, a small subfamily of bZip proteins consisting of DBP, TEF and HLF. It turned out that DBP protein and mRNA accumulation undergo circadian cycles with amplitudes in excess of one hundred-fold (Wuarin Schibler 1990). 

Incorporation of radioactivity derived from [14C] Leucine, [3H] Thymidine and [3H]2-deoxy glucose into normal and familial hypercholesterolemic homozygous fibroblasts incubated in fetal calf serum and lipoprotein deficient serum containing medium... 

In these experiments, normal and mutant cells (2 x 105 cells/dish) were seeded and grown for 6 days in 5 ml of medium supplemented with 10% fetal calf serum and antibiotics. On the 6th day, medium was removed and the monolayers washed twice with PBS/2% BSA and 5 times with PBS at room temperature. Two ml of fresh medium containing 1 y Ci each of L-[U C] leucine,... 

Serum Diabetic nephropathy (DN) Healthy subjects 25 DN patients 8 type 2 diabetes mellitus patients 33 UPLC Q-TOF MS Leucine, dihydrosphingosine, and phytosphingosine (54)... 

Fig. 5.1. Effect of increased NaCl concentration of the incorporation of [3H]uridine and [3H]leucine into CHO cells. Hamster CHO cells were set up as coverslip cultures in a multiwell dish in Eagle s medium (Glasgow modification) containing 10% calf serum (105 cells/0.5 ml). After overnight growth, 10 /x 1 of [3H]uridine (0.5 pCi) or [3H]leucine (2 fxCi) was added per well, and 30 min later 10 fil 5 M NaCl was added to half the wells. Coverslips were harvested at the indicated times and washed twice in ice-cold BSS, 4 times in cold 5% TCA and twice in absolute ethanol. The cells were dissolved in 0.5 ml hyamine hydroxide and the radioactivity counted using a scintillator of 0.5% diphenyloxazole in toluene. , Control, i.e. 120 mM NaCl o, 220 mM...

The remarkable similarity in the molar ratios of the amino acids offers encouragement to the proposition that common peptides will be found in the electrophoretic components of the serum proteins. The peptide of spot 7 probably differs from spot 8 in leucine content, which would account for the higher Rf of spot 8. More encouraging are the recent reports of Edelman (2, 13) who found that gamma-globulin, the Bence-Jones proteins, and the myeloma proteins have a peptide unit of common amino acid composition. 

SK Gupta, M Aziz, AA Khan (1989) Serum leucine aminopeptidase estimation a sensitive prognostic indicator of invasiveness in breast carcinoma, Indian J Pathol Microbiol 32 301—305... 

Similar results have been reported for polymorphisms at amino acid 55, with the PONl paraoxonase activity in blood serum from 55M (methionine) homozygotes reduced compared to either the 55L (leucine) homozygotes or the LM heterozygotes (Mackness et al, 1997). While it is intuitive that the rate of detoxification of a substrate would be dependent on the expression levels of these endogenous enzymes, the effects of the genetic polymorphisms suggest that catalytic efficiency is an equally important consideration. 

Takahasfai N, Takahashi Y, Putnam FW. Periodidty of leucine and tandem repetition of a 24-amino add segment in the primary structure of leucine-ridi a2-glycoprotein of human serum. Proc Natl Acad Sd U S A 1985 82 1906-10. 

ENl 16 Mauck, J., Warren, H. and LaTart, D. (1992). Development of a thin-film colorimetric assay for serum leucine aminopeptidase. Clin. Chem. 38, 985-986, Abstr. 217. 

Tsuji K, Soya Y, et al. Kinetic assay of serum and urine for urea with use of urease and leucine dehydrogenase. Clin Chem 1997 43 1932-6. 

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