Aromatic interactions and rotational strengths within protein environment: An electronic structural study on β-lactamases from class A

Abstract The Circular Dichroism (CD) spectrum of β-lactamase from Escherichia coli (TEM-1) has been calculated with the matrix method on the basis of the x-ray diffraction structure. All known transitions in the peptide and side-chain groups, especially the aromatic and disulfide groups have been included. The calculations were performed with and without the tryptophan (Trp) residues. Rotational strengths calculated with the matrix method were combined with Gaussians to generate the CD spectrum. The calculated spectrum reproduces the signs and approximate magnitudes of the CD bands rather w ell only when the trytophan side chains are included. However, the experimental negative double band at 208 and 222 nm, which is characteristic for a-helices, is absent in the calculated spectrum.

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Comparative theoretical study of the mechanisms of generation of rotational strengths in the near-UV in β-lactamases from class A

Chemical Physics Letters ◽

10.1016/j.cplett.2004.09.099 ◽

2004 ◽

Vol 398 (4-6) ◽

pp. 511-516 ◽

Cited By ~ 7

Author(s):

Tatyana Karabencheva ◽

Christo Christov

Keyword(s):

Theoretical Study ◽

Class A ◽

Rotational Strengths

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An Ultra-Structural Study of Human Melanoma in Vivo and Vitro

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091275 ◽

1976 ◽

Vol 34 ◽

pp. 258-259

Author(s):

James R. Gaylor ◽

Fredda Schafer ◽

Robert E. Nordquist

Keyword(s):

Endoplasmic Reticulum ◽

Golgi Apparatus ◽

Protein Aggregation ◽

Structural Study ◽

Human Melanoma ◽

Protein Matrix ◽

Early Form ◽

Endoplasmic Reticulum Protein ◽

Mitochondrial Origin

Several theories on the origin of the melanosome exist. These include the Golgi origin theory, in which a tyrosinase-rich protein is "packaged" by the Golgi apparatus, thus forming the early form of the melanosome. A second theory postulates a mitochondrial origin of melanosomes. Its author contends that the melanosome is a modified mitochondria which acquires melanin during its development. A third theory states that a pre-melanosome is formed in the smooth or rough endoplasmic reticulum. Protein aggregation is suggested by one author as a possible source of the melanosome. This fourth theory postulates that the melanosome originates when the protein products of several genetic loci aggregate in the cytoplasm of the melanocyte. It is this protein matrix on which the melanin is deposited. It was with these theories in mind that this project was undertaken.

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