Further tests on human enamel protein

Pincus, P.

doi:10.1042/bj0420219

Cited by 8 publications

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“…The organic matrix constitutes approximately 20% of the enamel in embryonic teeth (43)(44)(45)(46), but only 0 .5% in the adult when mineralization is completed (12,(47)(48)(49) . The matrix is mainly composed of protein (45, 50-53) with 1 .5-2% carbohydrates in mature human and bovine enamel (12,13,54) and 1 % in embryonic bovine enamel (17) . The carbohydrates are in the form of glycoprotein (12)(13)(14)(15)(16)(17) and mucopolysaccharide (15) .…”

Section: Presence Of Glycoprotein In the Organic Matrix Of Enamelmentioning

confidence: 99%

Elaboration of the Matrix Glycoprotein of Enamel by the Secretory Ameloblasts of the Rat Incisor as Revealed by Radioautography After Galactose-3h Injection

Weinstock

Leblond

1971

The Journal of Cell Biology

174

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The elaboration of enamel matrix glycoprotein was investigated in secretory ameloblasts of incisor teeth in 30-40-g rats . To this end, the distribution of glycoprotein was examined histochemically by the use of phosphotungstic acid at low pH, while the formation of glycoprotein was traced radioautographically in animals sacrificed 2 .5-30 min after galactose3 H injection . Histochemically, the presence of glycoprotein is observed in ameloblasts as well as in the enamel matrix ; in ameloblasts glycoprotein occurs within the Golgi apparatus in amounts increasing from the outer to the inner face of the stacks of saccules, and is concentrated in condensing vacuoles and secretory granules ; in the enamel matrix, glycoprotein is observed within linear subunits . Radioautographs at 2 .5 min after injection demonstrate the uptake of galactose-3H label by Golgi saccules, indicating that galactose 3H is incorporated into glycoprotein within this organelle. After 5-10 min, the label collects in the condensing vacuoles and secretory granules of the Golgi region . By 20-30 min, the label appears in the secretory granules of the apical (Tomes') processes, as well as in the enamel matrix (next to the distal end of the apical processes, and at the tips of matrix prongs) . In conclusion, galactose contributes to the formation of glycoprotein within the Golgi apparatus . The innermost saccules then distribute the completed glycoprotein to condensing vacuoles, which later evolve into secretory granules. These granules rapidly migrate to the apical processes, where they discharge their glycoprotein content to the developing enamel .

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Section: Presence Of Glycoprotein In the Organic Matrix Of Enamelmentioning

confidence: 99%

Elaboration of the Matrix Glycoprotein of Enamel by the Secretory Ameloblasts of the Rat Incisor as Revealed by Radioautography After Galactose-3h Injection

Weinstock

Leblond

1971

The Journal of Cell Biology

174

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“…10 He found tyrosine in the material and stated that it resists enzyme attack. Neither Kanner8 nor Pincus"0 gave any quantitative data.…”

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confidence: 99%

The Chemical Nature of the Proteins From Human Enamel

Losee

Hess

1949

J Dent Res

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A KNOWLEDGE of the composition of enamel is essential to an understanding of the processes of dental caries. While considerable work has been done on the inorganic portion of enamel, less attention has been given to the organic part. This paper describes some experiments on the isolation of the enamel proteins and the determination of their cystine, methionine, and phenylalanine content.Karlstrom, from micro-Kjeldahl determinations, calculated that the protein content of enamel ranged from 0.1 to 0.66 per cent with an average value of 0.3 per cent.' Sprawson, using enamel filings, found 0.15 per cent protein based on nitrogen determinations, and from carbon analysis, 0.18 to 0.21 per cent protein.2 Rosebury and Gies isolated enamel protein by dialysis and reported 0.3 to 0.54 per cent in human enamel.3 These investigators recognized the presence of a surface cuticle and an inner layer, and attempted to remove both prior to isolation of the protein. Armstrong and Brekhus determined the nitrogen content of the enamel from four normal teeth to be 0.098 per cent equivalent to not more than 0.60 per cent protein.4 LeFevre and Manly employed a semiquantitative method for the determination of the organic content of enamel.5 They deducted the moisture and inorganic content from the original weight of the enamel and found from 0.6 to 2.9 per cent, with an average value of 1.7 per cent total organic material. Deakins and Volker determined the total nitrogen content of enamel from rat teeth and calculated the protein content to be 2.97 per cent, while the enamel from old noncarious permanent human teeth gave a value of 1.75 per cent protein. It is of interest to note that they found, by this method, 0.49 per cent protein in the enamel of various, young, permanent human teeth.Since the amount of protein in enamel is quite small it is not surprising that very few investigators have attempted to study its amino acid content. Pincus was unable to find any sulfur in enamel protein and stated that it is a scleroprotein resembling reticulin.7 He based the latter statement of the finding that it is resistant to enzymatic hydrolysis. Pincus gives no quantitative data nor does he state the amount of protein isolated or tested. Kanner was unable to find cystine in an hydrolysate of enamel protein by the polarographic method of Heyrovsky.8 Schoeller, as reported by Pincus, found from one to two per cent sulfur in enamel protein.9 More recently Pincus has reported the isolation of what he calls "enamel protein" but which should more properly be termed

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