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Titolo:
A PHYSIOLOGICAL-FUNCTION FOR ALKALINE-PHOSPHATASE - ENDOTOXIN DETOXIFICATION
Autore:
POELSTRA K; BAKKER WW; KLOK PA; HARDONK MJ; MEIJER DKF;
Indirizzi:
UNIV GRONINGEN,DEPT PHARMACOKINET & DRUG DEL,A DEUSINGLAAN 1 NL-9713 AV GRONINGEN NETHERLANDS UNIV GRONINGEN,DEPT PATHOL NL-9713 AV GRONINGEN NETHERLANDS UNIV GRONINGEN,INST DRUG EXPLORAT NL-9713 AV GRONINGEN NETHERLANDS
Titolo Testata:
Laboratory investigation
fascicolo: 3, volume: 76, anno: 1997,
pagine: 319 - 327
SICI:
0023-6837(1997)76:3<319:APFA-E>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTRACELLULAR COMPARTMENT; HUMAN-NEUTROPHILS; BACTERIAL LIPOPOLYSACCHARIDE; REDUCES MORTALITY; HEPATIC-INJURY; RAT; ENZYME; COMPLEMENT; PROTEINS; SHOCK;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
K. Poelstra et al., "A PHYSIOLOGICAL-FUNCTION FOR ALKALINE-PHOSPHATASE - ENDOTOXIN DETOXIFICATION", Laboratory investigation, 76(3), 1997, pp. 319-327

Abstract

Alkaline phosphatase (AP), a common enzyme present in many species including humans, has been studied extensively. Although the enzyme is routinely applied as a marker for liver function, its biologic relevance is poorly understood. The reason for this is obvious: the pH optimumof AP in vitro, as measured with the usual test substrates (+/- 10.5), greatly exceeds the physiologic pH range as it occurs in biologic tissues. We now hypothesize that this relatively high pH optimum in vitro is related to dissociation of acidic groups in the protein preparation, which leads to the formation of negatively charged groups in the vicinity of the active site of the enzyme. These negatively charged groups may promote the activity of AP. We examined the possibility that endotoxin is a natural substrate for this enzyme because this phosphorylated substance is able to supply multiple negatively charged residuesin the microenvironment of the enzyme at a physiologic pH level. Phosphate groups in the endotoxin molecule are known to be essential for the biologic activities of this bacterial product. The present study demonstrates that in intestinal and renal tissue specimens in vitro, AP is endowed with endotoxin dephosphorylating activity at pH levels closer to the physiologic range. This is also illustrated by our experiments in vivo showing that the toxicity of endotoxin is significantly reduced after exposure to AP preparations, as tested by inducing a local intradermal inflammatory reaction in rats. Collectively, our data suggest that the ubiquitous enzyme AP may accomplish protection against endotoxin, an equally ubiquitous product of Gram-negative bacteria that may cause lethal complications after an infection with these micro organisms.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/10/20 alle ore 05:20:22