protein interactions

Question 1

how do enzymes bring substrates in close proximity to each other to facilitate a low energy state?

Answer 1

• bend substrate
• provide electron donors
• provide electron acceptors

Question 2

what is hemocyanin?

Answer 2

large O2 transport protein complex

Question 3

EF-Tu

Answer 3

active state? - EF-Tu binds GTP

over time, GTP hydrolyses to GDP, inactivating ef-tu

Question 4

SH2 domain

Answer 4

binds phosphorylated tyrosine
involved in forming signalling complexes
interaction = ionic interactions between negatively charged phosphate and positively charged amino acids

Question 5

SH3 domain

Answer 5

binds proline rich motifs
consensus sequence = prolines separated by 2 amino acids
found in adaptor proteins and signalling proteins
maintains multiprotein complexes
interaction = electrostatic interactions due to aromatic stacking

Question 6

PH domain

Answer 6

binds phospholipids
role = localises proteins to membranes
+ signalling
interaction = hydrophobic and charged

Question 7

EF hand

Answer 7

octadentate - 7 oxygens sheilding Ca2+/Mg2+
2 alpha helices with a loop region
invariant glycine accommodates oxygen containing side chains tightly turning around the Ca2+

Question 8

calmodulin

Answer 8

contains 4 EF hands
binds to 2 Ca2+ on each side
Ca2+ binding exposes hydrophobic patch on calmodulin + enables calmodulin to bind to amphipathic alpha helices
regulatory

Question 9

which proteins are calmodulin structurally highly related to?

Answer 9

troponin C

S100