RESUMO
Electron microscopic studies demonstrated that lesions were produced on the endotoxic lipopolysaccharide (LPS) as well as on the cell surface of V. alcalescens after reaction with fresh guinea pig serum. These lesions were approximately 90 A in diameter, and were seen on two characteristic structural entities derived from LPS preparations after incubation with serum. The use of numerous inhibitors, inactivators, and reaction conditions affecting hemolytic C' activity revealed that these lesions were mediated by the C' system. Concomitant with lesion formation, C' was fixed; the effect on classical C'3 activity was pronounced. It is concluded that endotoxic LPS, as contained in the outer three-layered membrane of the bacterial cell, is a substrate for the C' enzymes. It is suggested that certain biological activities of endotoxin may derive from its effects on the C' system.
Assuntos
Proteínas do Sistema Complemento , Soros Imunes , Lipopolissacarídeos , Veillonella/imunologia , Silicatos de Alumínio , Testes de Fixação de Complemento , Endotoxinas , Hemólise , Microscopia Eletrônica , Muramidase/análise , Polissacarídeos Bacterianos , gama-GlobulinasRESUMO
Extraction with alkaline sodium glycinate of the periodic fibril and unit structure of human amyloid and subsequent acidification of the extract provided a method for the purification as well as for the reconstitution of the periodic rod and of the unit structure. Guanidine completely solubilized and irreversibly dissociated both the rod and the unit structure of the human amyloid fibril.
Assuntos
Amiloide , Glicina/farmacologia , Guanidinas/farmacologia , Miocárdio , Baço , Eletroforese , Humanos , Microscopia Eletrônica , UltracentrifugaçãoRESUMO
"Amyloid" fibrils have been created from some human Bence Jones proteins by proteolytic digestion under physiologic conditions. These fibrils with an antiparallel, beta-pleated sheet conformation consist of only a portion of the variable region of the immunoglobulin light polypeptide chain and share the physical properties of amyloid fibrils. The relation between amyloidosis and immunoglobulins is thus more firmly established and a pathogenetic mechanism for amyloid fibril formation is suggested.
Assuntos
Amiloide/biossíntese , Proteína de Bence Jones/metabolismo , Sequência de Aminoácidos , Amiloide/análise , Humanos , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Microscopia Eletrônica , Peptídeo Hidrolases , Temperatura , Difração de Raios XRESUMO
This report suggests a mechanism for collagen degradation mediated by human granulocytic leukocytes. A specific collagenase, which is extractable from human granulocytes, has been partially purified by DEAE chromatography. This collagenolytic enzyme is operative at physiological pH and is inhibited by EDTA, cysteine, and reduced glutathione but not by human serum. The enzyme cleaves the collagen molecule into two specific products, without loss of helical conformation. Electron micrographs of segment long spacing aggregates indicate that the cleavage occurs one-quarter of the length from the carboxy terminal end of the molecule. Experiments with crude extracts from granulocytes suggest that the specific products of granulocyte collagenase activity are then degraded by other proteases present in the human granulocyte.