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Topic: Tolerance of amino acid substitution  (Read 3262 times)

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Offline coolusername

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Tolerance of amino acid substitution
« on: October 05, 2013, 05:01:39 PM »
I need your feedback on this question. Specifically the rating of each position. A sequence of sequence alignment is shown. For positions 61-66 comment briefly, but specifically, on the the character of the amino acids present in that position. Rate each position on the tolerance of amino acid substitution.

1= No substitution tolerated
2= highly conservative substitutions are tolerated
3= moderately conservative substitutions are tolerated
4= nonconservative substitutions are occasionally tolerated
5= most substitutions appear to be allowed

61 62 63 64 65 66
V   A  S   E  R  A
V   Y  N   R  K  A
I    L  D   Q  K  G
V   Q  S   K  R  G
V   K  N   R  K  G
I    S  S   E  H  A
I    M D   Q  K  A

My thoughts:
Position 61: Valine and isoleucine residues reside at this position. They could be used for structural support (hydrophobic effect).

Position 62: This position has many different amino acids with different properties. It may indicate that that position on the polypeptide is not a big factor for its main function.

Position 63: This position contains uncharged polar residues. It may just contribute to H-bonds for structural support.

Position 64: This position has residues with sides chains that are ionizable. It may contribute to enzymatic activity.

Position 65: This position has side chains that are basic.

Position 66: Non-polar residues, contribution to hydrophobic effect.

Ratings:
Position 61: 2 Only valine and isoleucine.
Position 62: 5 Many different amino acids with different properties/characteristics
Position 63: 4 Mainly uncharged polar groups (S and N) with aspartic acid.
Position 64: 4 Mainly amino acids with charged side chains.
Position 65: 3 Only 1 histidine but arginine and lysine repeats.
Position 66: 2 Only alanine and glycine

I'm having trouble on positions 51, 53-56.
Any help would be great.

Offline coolusername

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Re: Tolerance of amino acid substitution
« Reply #1 on: October 07, 2013, 06:00:29 PM »
Sorry I should have said 61, 63-66

Offline Babcock_Hall

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Re: Tolerance of amino acid substitution
« Reply #2 on: October 08, 2013, 05:31:15 PM »
What similarities do you see between the two amino acids at position 66, for example?  With respect to 63, does D have a charge?  With respect to 64 are the charges the same or different?
« Last Edit: October 08, 2013, 07:06:04 PM by Babcock_Hall »

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