PubMed Health⌕ Search

Biomedical subjects

P T Turkington

Publications and source records attributed to P T Turkington.

8 recordsLinked to original sources
PubMed1994

An enzyme immunoassay of human polymorphonuclear leukocyte cathepsin G.

An enzyme immunoassay has been developed for the quantitation of human polymorphonuclear leukocyte cathepsin G. The assay had a linear relationship over the range 0.23-4.7 nmol/l (6-125 ug/l) and a detection limit of 0.23 nmol/l (6 ug/l). Recovery in citrated plasma only occurred when the concentration was higher than 4.0 umol/l (110 mg/l). This effect could be overcome by diluting the plasma before adding the proteinase or by inactivating the proteinase before diluting it with plasma. The failure to detect cathepsin G in plasma was due to the plasma inhibitor alpha-2-macroglobulin masking the antigenic sites of the proteinase. Samples from several types of leukemia showed no detectable cathepsin G even when the total myeloid count was up to ten times the normal.

Cathepsin G↗
PubMed1992

Cathepsin G, a regulator of human vitamin K, dependent clotting factors and inhibitors.

Cathepsin G was used in vitro to digest human factor VII and factor IX. Clotting assays indicated that the proteinase affected a rapid loss in coagulant activity while in the presence of calcium ions the activity was almost totally protected. SDS-polyacrylamide gel electrophoresis indicated the removal of a peptide from each zymogen, VII-L from factor VII and IX-L from factor IX. This lead to the formation of VII-H and IX-H respectively. N-terminal analysis of the VII-H and IX-H products and COOH-terminal analysis of the VII-L and IX-L products confirmed that cathepsin G had cleaved position Phe40:Trp41 in factor VII and factor IX. The cleavage site is the same as that when cathepsin G is reacted with factor II, factor X and protein C. The unique action of cathepsin G may be part of a regulatory system for controlling the coagulant activity of vitamin K dependent clotting in vivo.

Amino Acid Sequence↗
PubMed1991

Cathepsin G can produce a gla-domainless protein C in vitro.

Human polymorphonuclear leucocyte cathepsin G was used in vitro to digest human protein C. Anticoagulant assays showed that the proteinase affected a rapid loss in the anticoagulant activity of the zymogen. Calcium ions almost totally protected the anticoagulant activity of protein C against the action of cathepsin G. Polyacrylamide gel electrophoresis, in the presence of SDS (non reducing conditions), indicated that the proteolytic action of cathepsin G lead, to the removal of a peptide of low molecular mass (PC-L'') from protein C with the consequent formation of a product of high molecular mass (PC-P). Electrophoresis in the presence of SDS (reducing conditions) showed that the PC-L'' fragment was removed from the light chain of protein C (PC-L). N-terminal amino acid analysis of the PC-P product and COOH terminal amino acid analysis of PC-L'' product confirmed that cathepsin G had cleaved position Phe40:Trp41 in the light chain. This cleavage was responsible for removal of the gamma-carboxyglutamic acid (gla) containing region of protein C.

Amino Acid Sequence↗
PubMed1991

Degradation of human factor X by human polymorphonuclear leucocyte cathepsin G and elastase.

Cathepsin G and elastase from human polymorphonuclear leucocytes were used in vitro to digest human factor X. Clotting assays showed that both proteinases affected a rapid loss in the coagulant activity of factor X. Calcium ions almost totally protected the coagulant activity of factor X against the action of cathepsin G but not elastase. Polyacrylamide gel electrophoresis (in nonreducing conditions and in the presence of SDS) indicated that the proteolytic action of cathepsin G led to the removal of a peptide of low molecular mass (pX) with the consequent formation of a single stable high molecular mass product (PX). SDS electrophoresis (under reducing conditions and in the presence of SDS) indicated that a pX was derived from the light chain of factor X. The proteolytic action of elastase led to the formation of numerous degradation products. Analysis of the products generated by the action of cathepsin G indicated that cathepsin G cleaved position Phe40:Trp41 in the light chain of factor X. In the presence of citrated plasma, cathepsin G but not elastase, was responsible for a loss in coagulant activity.

Amino Acid Sequence↗
PubMed1986

The degradation of bovine and human prothrombin by human polymorphonuclear leukocyte cathepsin G.

Cathepsin G, isolated from human polymorphonuclear leukocytes, was found to effect rapid and specific degradation and biological inactivation of bovine and human prothrombin in the absence of calcium ions with the formation of two peptide fragments from the N-terminal end of the molecule. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate indicated that the molecular weights of the fragments were 5,000 and 17,500. Proteolysis of prothrombin by cathepsin G was inhibited by calcium ions. Leukocyte proteinases such as cathepsin G may be responsible for haemorrhagic disorders associated with myelocytic leukaemia and septicaemia.

Amino Acids↗
PubMedDate not supplied

Cathepsin G inactivates human protein S in vitro.

Human polymorphonuclear leukocyte cathepsin G was used in vitro to digest human protein S. While clotting assays indicated that the proteinase induced a rapid decrease in activity, polyacrylamide gel electrophoresis-sodium dodecyl sulphate indicated the removal of a peptide of low molecular mass product protein S (des 1-40). The loss in activity was the result of cathepsin G cleaving position Phe40-Tyr41 and removing the calcium-binding region. Calcium ions almost totally protected the cofactor from the action of cathepsin G in vitro.

Amino Acid Sequence↗