Complex II contains five prosthetic groups and four different protein subunits;
a. Subunits A and B extend into the matrix; they contain three 2Fe-2S centers, bound FAD, and a
binding site for the substrate, succinate
b. Subunits C and D are integral membrane proteins, contain a heme group, heme b, and a binding
site for ubiquinone,

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#Unit 1. Molecules and their Interaction Relevant to Biology

H bonding i-i+3, i+1 in BS while i+2 in below LHH which virtually not allowed region

for most of amino acid except Gly that is why Gly is most conserved in type II B turns

                                                                Type II β turn

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#Unit 1. Molecules and their Interaction Relevant to Biology

                  Type l'β turn

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#Unit 1. Molecules and their Interaction Relevant to Biology

                              Type II β turn

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#Unit 1. Molecules and their Interaction Relevant to Biology

#Id: 7711

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                                 α-Turn

Contains hydrophilic amino acids and protrudes outside the protein surface like a hook.

Consists of 5 amino acids, generally termed as i, i+1, i+2, i+3 and i+4

H-bond is seen between i and i+4 (First and Fifth residue)

The conformation of i+1, i+2 and i+3 are crucial and on the basis of this, they are classified into

9 groups

#Id: 7712

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                γ-Turn

Consists of 3 amino acids, generally termed as i, i + 1 and i + 2

H-bond is seen between i and i + 2 (First and Third residue)

The conformation of i + 1 is crucial and on the basis of this, they are classified into 2 groups

The dihedral angles of residue i + 1 are (70, -60) and (-70, 60) of the classical and inverse gamma turns