*I really only need the fourth question answered. Thank you* Look at the followi

Question

*I really only need the fourth question answered. Thank you*

Look at the following amino-acid sequences from two warm-water species and one cold-water species and identify where changes in the sequence occurred.

Line 1: C. punctipinnis:Temperate (cold-adapted) Line 2: C. caudalis:Tropical(warm-adapted) Line 3: C. xanthochira: Tropical (warm-adapted)

151 GFERHRVIGS GTNLDSARFR HIMGEKLHLH PSSCHGWIVG EHDGSSVPVW GFERHRVIGS GTNLDSARFR HIMGEKLHLH PSSCHGWIVG EHDGSSVPVW GFERHRVIGS GTNLDSARFR HIMGEKLHLH PSSCHGWIIG EHDGSSVPVW

201 SGVNVAGVSL QGLNPQMGTD GDSEKWKEVH KLVVDGAYEV IKLKGYTSWA SGVNVAGVSL QALNPQMGAE GDSENWKAVH KQVVDGAYEV IKLKGYTSWA SGVNVAGVSL QGLNPKMGAE GDSENWKEVH KLVVDGAYEV IKLKGYTSWA 251 IGMSVADLVE SIMKNLHKVH PVSTLVQGMH GVKDEVFLSV PCVLGNSGLT IGMSVADLVE SIMKNLHKVH PVSTLVQGMH GVKDEVFLSV PCVLGNSGLT IGMSVADLVE SIMKNLHKVH PVSTLVQGMH GVKDEVFLSV PCVLGNSGLT

301 DVIHMTLKPE EEKQLVKSAE TLWGVQKELT DVIHMTLKPD EEKVLVKSAE TLWGVQKELT DVIHMTLKPD EEKQLVKSAE TLWGVQKELT

Which amino acids changed between the three species? List four of them below, using the number of the amino acid. Example: Amino acid 189 changed from valine to isoleucine in a warm adapted species. 1) _______________________________________________________________ 2) _______________________________________________________________ 3) _______________________________________________________________ 4) _______________________________________________________________ What were the changes in the chemical properties of the R-groups? Use the amino-acid chart to in the Powerpoint file to answer this question. Example: Both valine and isoleucine are nonpolar. 1) _______________________________________________________________ 2) _______________________________________________________________ 3) _______________________________________________________________ 4) _______________________________________________________________ How might the changes that you identified affect the protein’s structure? Example: The change would likely have no effect. Neither valine and isoleucine would promote hydrogen bonding with water, because their R groups are nonpolar and thus hydrophobic. 1) _______________________________________________________________ 2) _______________________________________________________________ 3) _______________________________________________________________ 4) _______________________________________________________________

4. Assuming that the mutations are adaptive, how should the changes that you identified affect the stability of the protein at low and high temperatures?

Explanation / Answer

The impact of point mutations on the thermal stability is decided through Tm (melting temp)which measures how the protein melting temperature changes upon mutations.  An improved packing is the cause of the increased stability for a given protein.

a. Amino acid 212 is changed from Glycine to Alanine in warm adapted species. b. Amino acid 216 is changed from Glutamine to Lysine in warm adapted species.

The adaptation to cold is achieved through a decrease in the activation energy, which results from an increased protein flexibility, either of the whole protein or of a specific domain in some multidomain proteins. Although the strategy of adaptation is unique to each enzyme, it has been observed that amino-acid residues involved in the catalytic mechanism are generally conserved in psychrophilic and mesophilic enzymes. Several sequence patterns have been associated with psychrophilic adaptations, such as decreased levels of Pro and Arg residues, weakening of intramolecular interactions, increased solvent interactions, decreased charged residues interactions, and disulfide bonds. Increased levels of Gly residues or the establishment of Gly clusters have been frequently suggested to be associated with psychrophilicity. This could be a result of increased local structural flexibility due to the intrinsic flexibility of Gly residues. Thus a change from Glycine to alanine is an indication of loss of psychrophilic character.

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