Human Erythrocytes Peptidases

Vitale, Ljubinka; Abramić, Marija; Zubanović, M.

doi:10.1016/b978-0-08-027377-8.50022-1

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…It was activated by Co2" and showed a preference for Lys-and Arg-substrates but also hydrolysed Leu-and Ala-2-naphthylamides at 480% and 120% respectively of the rate of the Lys-substrate. It was also sensitive to EDTA, being fully inhibited at 1 mM, and had IC50 values of 27 pM and 150,M for amastatin and bestatin respectively (Vitale et al, 1981). A later report on what seems to be a similar enzyme gave further IC50 values: EDTA, 0.9,M; amastatin, 90 nM; bestatin, 1 uM; puromycin, 2.5,M.…”

Section: Localization Of Jurkat Cell Aminopeptidase Activitymentioning

confidence: 88%

The aminopeptidase activity in the human T-cell lymphoma line (Jurkat) is not at the cell surface and is not aminopeptidase N (CD-13)

Turner

Kenny

1994

Biochemical Journal

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Although lymphocytes are CD-13-negative and therefore should not express the ectoenzyme aminopeptidase N (AP-N), there have been a number of reports suggesting the presence of a cell-surface aminopeptidase with many similarities to AP-N. We have determined aminopeptidase activity with 4-methyl-7-coumarylamide (NMec) derivatives of alanine, leucine, lysine and arginine in Jurkat cells (a human T-cell lymphoma line) and in HL60 cells (a CD-13-positive myeloid leukaemia line) and compared the activities with those of purified pig AP-N and human renal microvillar membranes. Jurkat cell aminopeptidase activity doubled on disrupting the cells and the sensitivity to amastatin increased. When the cells were fractionated only 4% of the activity was recovered in the membrane fraction, compared with 87% recovery for alkaline phosphatase. The profile of activities for intact Jurkat cells was Leu > Ala > Lys > Arg, changing in the cytosolic fraction to Lys > or = Arg > Leu = Ala; the profiles for intact HL60 cells and AP-N were identical, namely Ala > Leu > Arg > Lys. The Km values for the hydrolysis of Ala-NMec and Leu-NMec by Jurkat cells were 65 microM and 11 microM, in each case some 6-fold lower than those for AP-N. The pH-activity curves for the hydrolysis of Ala-NMec by Jurkat cells and human renal microvillar membranes were displaced by almost 1 pH unit and the activity was not sensitive to the anionic composition of the buffers. However, a 3-fold activation of the cytosolic activity by 0.1 M NaCl was observed with Arg-NMec as substrate. With Ala-NMec as substrate, the sensitivity of the aminopeptidase activity to inhibitors increased markedly after disrupting the cells, but still differed from that observed with purified pig AP-N; the concentrations giving 50% inhibition were as follows (values for AP-N in parentheses): amastatin. 28 nM (150 nM); bestatin, 12 microM (43 microM), probestin, 100 nM (< 10 nM), puromycin, 30 microM (> 1 mM). Anion exchange chromatography on Mono Q revealed two activities: that of peak I preferentially hydrolysed Arg-NMec, was activated by NaCl and was insensitive to amastatin; while that of peak II was strongly inhibited by amastatin and had a broad specificity.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Localization Of Jurkat Cell Aminopeptidase Activitymentioning

confidence: 88%

The aminopeptidase activity in the human T-cell lymphoma line (Jurkat) is not at the cell surface and is not aminopeptidase N (CD-13)

Turner

Kenny

1994

Biochemical Journal

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“…Reports on several APs from blood cells, able to hydrolyze Arg-2NA [1][2][3][4][5][6], rose a question of their similarity and belonging to one of the already established groups of APs [7], To clear dilemmas concerning AP from human red blood cells which we have previously described [2], a new isolation procedure for this enzyme was developed and the study of its properties was extended. Therefore more extensive data on catalytic properties and specificity are needed to compare and classify these enzymes properly.…”

Section: Introductionmentioning

confidence: 99%

Basic Amino Acids Preferring Broad Specificity Aminopeptidase from Human Erythrocytes

Abramić

Vitale²

1992

Biological Chemistry Hoppe-Seyler

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An aminopeptidase hydrolyzing 2-naphthylamides of Lys, Arg, Leu, Met, Phe and Tyr, as well as different di-to tridecapeptides, was purified from the cytosol of human erythrocytes. The enzyme showed preference for Lys and Arg at N-terminus, as proline and D-amino acids were nonpermissive at P 1 ' site. Higher affinity for oligopeptides than for aminoacyl naphthylamides was observed. Among the substrates were Lys-bradykinin, angiotensin III, thymopentin and enkephalins. Aminopeptidase was shown to be a monomeric protein of Mr~110000 and of pl~4.8, activated by Co 2 * and inhibited by EDTA, pHMB, amastatin, bestatin and puromycin. The isolated enzyme could be classified as cytosolic, Lys(Arg) preferring, broad specificity aminopeptidase.Abbreviations: AP, aminopeptidase; 2NA, 2-naphthylamide; SDS, sodium dodecyl sulfate; pHMB, p-hydroxymercuribenzoate.

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Human Erythrocytes Peptidases

Cited by 2 publications

References 15 publications

The aminopeptidase activity in the human T-cell lymphoma line (Jurkat) is not at the cell surface and is not aminopeptidase N (CD-13)

The aminopeptidase activity in the human T-cell lymphoma line (Jurkat) is not at the cell surface and is not aminopeptidase N (CD-13)

Basic Amino Acids Preferring Broad Specificity Aminopeptidase from Human Erythrocytes

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