13433-04-0Relevant articles and documents
Transport and Metabolic Pathway of Thymocartin (TP4) in Excised Bovine Nasal Mucosa
Lang, Steffen,Langguth, Peter,Oschmann, Rainer,Traving, Birgit,Merkle, Hans P.
, p. 1190 - 1196 (1996)
Thymocartin (TP4, Arg-Lys-Asp-Val) is the 32-35 fragment of the naturally occuring thymic factor (thymopoietin). Here studies on the nasal transport and metabolism of TP4 were performed. Freshly excised bovine nasal mucosa was taken as a model membrane. For permeation studies typical donor-receiver experiments (side-by-side) and finite-dose experiments with small volumes of highly concentrated solutions were carried out. The metabolic pathway of TP4 in nasal mucosa was found to occur according to a typical amino-peptidase cleavage pattern, stepwise forming Lys-Asp-Val and Asp-Val. TP4 metabolism experiments under reflection kinetics showed a saturation profile above 0.5 μmol mL-1. A non-linear kinetic model consisting of three steps in sequence was sufficient to describe the kinetics: for the first step saturable Michaelis-Meat kinetics, and for the second and the third step first-order kinetics were assured. The model was capable of simultaneously fitting the data for the full range of initial concentrations from 0.1 up to 1.0 μmol mL-1. Saturation kinetics was also found to be the prominent feature of the permeation experiments performed. In the lower concentration range (-1), transport of TP4 across nasal mucosa was controlled by metabolism, in the higher concentration range (>0.85 μmol mL-1) diffusion control became more important. We conclude that enhancement of absorption can be achieved when nasal ammopeptidases are saturated, e.g. at high TP4 concentrations.
Isolation and identification of urinary β-aspartyl dipeptides and their concentrations in human urine
Tanaka,Nakajima
, p. 617 - 625 (2007/10/05)
β-Aspartyl-methionine, -aspartic acid and -glutamic acid and γ-glutamyl-threonine and -glycine were isolated and identified in human urine by means of ion-exchange chromatography, highvoltage paper electrophoresis, acid hydrolysis and determination of N-terminal amino acids of the isolated compounds, and comparison of their behaviors in paper electrophoresis and chromatography with those of the authentic compounds. The concentrations of acidic β-aspartyl dipeptides in human urine were determined using an amino acid analyzer. Their concentrations were as follows: β-aspartyl-glycine, male, 44.4±8.5, female, 61.4±18.9, child, 83.7±27.1; -alanine, male, 11.0±4.9, female, 20.7±12.0, child, 25.3±9.1; -glutamic acid, male, 10.0±3.7, female, 23.0±8.5, child, 20.4±7.5; -serine, male, 9.9±2.8, female, 13.6±3.8, child, 14.9±4.7; -aspartic acid, male, 4.3±1.0, female, 9.1±2.2, child, 18.4±6.5; -threonine, male, 3.9±0.9, female, 5.8±1.1, child, 13.2±4.9 μmol/g creatinine (mean ± S.D.). The order of the sum of their concentrations tended to be child>female>male. Patients receiving intravenous hyperalimentation also excreted acidic β-aspartyl dipeptides into urine in amounts similar to those in females and in a pattern similar to that observed in healthy persons. This finding indicates that urinary β-aspartyl dipeptides were probably of endogenous origin because oral nutrition was stringently excluded in these patients.