Studies of the secondary structures of amelogenin from bovine tooth enamel

Renugopalakrishnan, V.; Strawich, E.; Horowitz, Paul M.; Glimcher, Melvin J.

doi:10.1021/bi00365a023

Cited by 71 publications

(43 citation statements)

References 54 publications

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“…However, the FT-IR data of Pvt f is consistent with more of b-sheet and b-turn structure compared with others. The latter is in accordance with those obtained by Taborsky [38] and Renugopalakrishnan [39] as the b-type conformation is readily acquired by the protein in the absence of metal.…”

Section: Characterizations Of Pvt I and Pvt Fsupporting

confidence: 92%

Simply and effectively preparing high‐purity phosvitin using polyethylene glycol and anion‐exchange chromatography

Zhang

Qiu

Geng

et al. 2011

J of Separation Science

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An attempt was made to develop a new protocol for preparing phosvitin that could be easy scaled up using polyethylene glycol (PEG6000). Influence of PEG6000 concentration and pH of sample solution on phosvitin isolation was investigated. Phosvitin of high purity (99%) was obtained in good yield (47%) with the optimal condition of pH 4.0 and 3% PEG6000 precipitation. In addition, through evaluating different anion-exchange chromatography methods, the DEAE procedure at pH 7.5 was finally selected as the best procedure to obtain metal-free phosvitin that lost the least protein. Furthermore, it is observed that the purity and characterizations of prepared phosvitin were similar to those of the standard phosvitin from Sigma, and the random coil of phosvitin converted into more compact structure after removing metal ion. In conclusion, the developed method was simple and suitable for scaled up preparation of phosvitin.

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Section: Characterizations Of Pvt I and Pvt Fsupporting

confidence: 92%

Simply and effectively preparing high‐purity phosvitin using polyethylene glycol and anion‐exchange chromatography

Zhang

Qiu

Geng

et al. 2011

J of Separation Science

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“…When compared with traditional a-helix conformation having two minima at 208 and 222 nm, the trough of the 32 kDa enamelin at 220 nm is a little flat and slightly red shifted, which is likely due to the contribution from 10.1% b-sheet conformation. It is apparent that the CD spectrum of the 32 kDa enamelin is different from that of the principal enamel protein amelogenin, which has a high percentage of polyproline type II helix and unordered structures, as manifested by an earlier study (Renugoplakrishnan et al, 1986;Lakshminarayanan et al, 2007). This elliptically polarized difference indicates that the 32 kDa enamelin and rP172 amelogenin have their distinctive secondary structures and consequently may play different but complimentary roles during enamel formation.…”

Section: Analysis Of Secondary Structure Of the 32 Kda Enamelinmentioning

confidence: 91%

The 32kDa enamelin undergoes conformational transitions upon calcium binding

Fan

Lakshminarayanan

Moradian‐Oldak

2008

Journal of Structural Biology

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The 32 kDa hydrophilic and acidic enamelin, the most stable cleavage fragment of the enamel specific glycoprotein, is believed to play vital roles in controlling crystal nucleation or growth during enamel biomineralization. Circular dichroism and Fourier transform infrared spectra demonstrate that the secondary structure of the 32 kDa enamelin has a high content of alpha-helix (81.5%). Quantitative analysis on the circular dichroism data revealed that the 32 kDa enamelin undergoes conformational changes with a structural preference to beta-sheet with increasing concentration of calcium ions. We suggest that the increase of beta-sheet conformation in the presence of Ca(2+) may allow preferable interaction of the 32 kDa enamelin with apatite crystal surfaces during enamel biomineralization. The calcium association constant (K(a)=1.55 (+/-0.13)x10(3)M(-1)) of the 32 kDa enamelin calculated from the fitting curve of ellipticity at 222 nm indicated a relatively low affinity. Our current biophysical studies on the 32 kDa enamelin structure provide novel insights towards understanding the enamelin-mineral interaction and subsequently the functions of enamelin during enamel formation.

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“…The Tl1 cytoplasmic domain is extremely rich in prolines (27 out of 126) and contains a proline-rich region between amino acids 257 and 278 in which there are four histidines, each separated from one another by a stretch of precisely six amino acids. Such a region could provide a binding site for a cation or for a positively charged site on a macromolecule(s) (25).…”

mentioning

confidence: 99%

Molecular cloning and expression of T11 cDNAs reveal a receptor-like structure on human T lymphocytes.

Sayre¹,

Chang²,

Hussey³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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The T11 (CD2) sheep-erythrocyte-binding protein is a T-cell surface molecule involved in activation of T lymphocytes and thymocytes, including those lacking the T3-Ti antigen-receptor complex. The primary structure of Til was deduced from protein microsequencing and cDNA cloning. The mature human protein appears to be divided into three domains: a hydrophilic 185 amino acid external domain bearing only limited homology to the T-cell surface protein T4 and the immunoglobulin K light chain variable region, a 25 amino acid hydrophobic transmembrane segment, and a 126 amino acid cytoplasmic domain rich in prolines and basic residues. Transfection of cDNAs encoding either the 1.7-or the 1.3-kilobase Til mRNA into COS-1 cells resulted in expression of surface Til epitopes as well as sheep-erythrocyte-binding capacity. The predicted structure is consistent with the possibility that Til functions in signal transduction.Human thymus-derived (T) lymphocytes were originally distinguished from B lymphocytes and other hematopoietic cells by their ability to form spontaneous aggregates (E rosettes) with sheep erythrocytes (SRBCs) (1-3). Congenital hypoplasia of the thymus results in loss or significant diminution of peripheral blood E-rosette-forming cells, thus attesting to the importance of the thymus in the maturation of lymphocytes bearing surface receptors for SRBCs.The structure mediating the SRBC binding property is a 50-kDa single-chain cell surface protein (4)(5)(6)(7)(8). Three distinct surface epitopes termed T111, T112, and T113 can be defined. Whereas the T111 and T112 epitopes are expressed on both resting and activated T cells, T113 is spatially distinct and preferentially expressed after T-lineage activation. The SRBC binding site on T11 appears to be identical or closely associated with the T111 epitope, because antibodies to T111 but not T112 or T113 block the ability of SRBCs to form rosettes with T lymphocytes (8). Perhaps more important, antibodies to the T111 epitope also broadly inhibit T-cell responses. In contrast, a combination of anti-T112 plus anti-T113 induces interleukin 1 (IL-1)-independent polyclonal T-cell activation. Thus, interaction of monoclonal antibodies with the T11 structure produces either profound agonistic or antagonistic effects on T-cell activation.Stimulation of T cells through T11, like that occurring through the T3-Ti antigen/MHC receptor complex (which recognizes antigen in the context of major histocompatibility complex-encoded proteins), is mediated via an interleukin 2 (IL-2)-dependent pathway involving activation of endogenous IL-2 and IL-2-receptor genes (8). Nevertheless, these surface structures are not physically linked to one another, since (i) immunoprecipitation and comodulation studies fail to demonstrate any association between T11 and individual T3-Ti subunits (9) and (ii) the T11 pathway functions in early thymocytes and natural killer cells, both of which lack the surface T3-Ti complex (10, 11).Given that T11 is more phylogenetically conserved than any ...

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Studies of the secondary structures of amelogenin from bovine tooth enamel

Cited by 71 publications

References 54 publications

Simply and effectively preparing high‐purity phosvitin using polyethylene glycol and anion‐exchange chromatography

Simply and effectively preparing high‐purity phosvitin using polyethylene glycol and anion‐exchange chromatography

The 32kDa enamelin undergoes conformational transitions upon calcium binding

Molecular cloning and expression of T11 cDNAs reveal a receptor-like structure on human T lymphocytes.

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