The amino acid composition of proteins from the oral tissues—II: The matrix proteins in dentine and enamel from developing human deciduous teeth

Citric and lactic acids as root canal irrigants in vitro

Citrate in mineralized tissues. I. Citrate in human dentine.

Mucosacchar des and glycoproteins. Chemistry and physiopathology.

Association of free amino acids with caries experience and mutans streptococci levels in whole saliva of children with early childhood caries.

IN VIEW of the evidence for bacterial hydrolysis and destruction of the organic matrix as a basic etiological factor in caries formation,1 2, 3 it is logical that the proteins of dentin and enamel should be examined as to their amino acid content, the sequence of their amino acids, and the mode of combination of the proteins with the chondroitin sulfate of the matrix. In this report the initial studies on the amino acid composition of the insoluble material of decalcified dentin are detailed. This particular aspect has been the subject of several investigations4-7; most of these investigations have employed technics that have revealed useful information but lack the accuracy and precision of the methods of Moore and Stein8 as used in this study.

Amino acid composition of proteins of human dentin.

j EPORTS of the presence of a mueopolysaceharide in human enamel and dentin are found in the literature dating from 1937; Meyer and Smyth,1 Pincus,2 Stack,3 Hess and Lee,4 Rogers,5 and others have identified mucopolysaccharides in such materials. Sognnaes and Wislocki6 , verified these findings with histochemical technics. Hess4 and Pincus2 identified the mucopolysaccharide as chondroitin sulfuric acid, a compound that has long been recognized as a constituent of cartilaginous tissues and bone matrix. Chondroitin sulfuric acid is a polymer consisting of a sulfate grouping, acetic acid, galactosamine, and glucuronic acid. The first report of enzymatic breakdown of chondroitin sulfuric acid was made by Neuberg and co-workers.8' 9 They inferred that the enzymatic reaction was one of depolymerization with hydrolysis of the sulfuric acid group. The crude enzyme employed in this investigation was an alcohol-ether dried preparation of a gram-negative rod of the Pseudomonas order. In a more recent investigation, Pincus'0 reported the sulfatase activity of a gramnegative rod on chondroitin sulfuric acid. Schultz-Haudt and Scherp\" have investigated the chondrosulfatase activity of microorganisms isolated from human gingival crevices. The hydrolysis of chondroitin sulfate was measured by a turbidimetric procedure. These investigators isolated and characterized the responsible microorganism as a micro-aerophilic diphtheroid bacillus. In the process of isolation and characterization of these organisms, a number of other types and combinations, including many strains of streptococci, failed to show chondrosulfatase activity. The purpose of this investigation was to ascertain what action a crude enzyme preparation from bacteria associated with human dental caries might have on chondroitin sulfate. In view of recent investigations associating the streptococcus with dental caries,12, 13 it was decided to investigate this group of bacteria for possible enzymatic activity.

Lewis S. Earle

Papers

Amino acid composition of proteins of human dentin.

Bacterial hydrolysis of chondroitin sulfate.