E. coli has at least four individual topoisomerases (I through IV). Those of type I (topoisomerases I and III) generally, relax DNA by removing negative supercoils (increasing Lk).

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#Unit 1. Molecules and their Interaction Relevant to Biology

Structural Classification of Proteins database =SCOP

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CATH differs from SCOP in that it combines manual analysis with automation based on quantitative algorithms to classify protein structures.

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#Unit 1. Molecules and their Interaction Relevant to Biology

There are several major approaches to protein structure prediction.

The simplest and most reliable approach is

homology modeling, aligns the sequence of interest with the sequence of a homologous protein or domain of known structure—compensating for amino acid substitutions, insertions, and deletions—through modeling and energy minimization calculations.

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Threading is a computational technique that attempts

to determine the unknown structure of a protein by ascertaining

whether it is consistent with a known protein structure.

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#Unit 1. Molecules and their Interaction Relevant to Biology

Prediction of the structure of a protein based only on its chemical and physical properties is done by ab initio (from the beginning) methods is the Rosetta program

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#Unit 1. Molecules and their Interaction Relevant to Biology

About 75% of the charged residues in proteins are members of ion pairs that are located mostly on the protein surface.

Despite the strong electrostatic attraction interactions contribute little to the stability of a native protein.