SNARE complex is disassembled by ATP-dependent reaction mediated by cytosolic proteins, NSF & α-SNAP

TLS Online TPP Program

#Id: 8759

#Unit 1. Structure and Function of Biomolecules

Hydrogen bonds, which are central features of protein structures, make only minor contributions to protein stability.

TLS Online TPP Program

#Id: 8760

#Unit 1. Structure and Function of Biomolecules

This is because hydrogen-bonding groups in an unfolded protein form hydrogen bonds with water molecules. Thus the contribution of a hydrogen bond to the stability of a native protein is the small difference in hydrogen bonding free energies between the native and unfolded states (−2 to 8 kJ ∙ mol−1)

TLS Online TPP Program

#Id: 8761

#Unit 1. Structure and Function of Biomolecules

The Hydrophobic Effect Has the Greatest Influence on Protein Stability. The hydrophobic effect, which causes nonpolar substances to minimize their contacts with water, is the major determinant of native protein structure.

TLS Online TPP Program

#Id: 8762

#Unit 1. Structure and Function of Biomolecules

Thermostable proteins have such a high incidence of salt bridges.

TLS Online TPP Program

#Id: 8763

#Unit 1. Structure and Function of Biomolecules

Thermophilic proteins have increased amounts of Arg, increased occurrence of Ala in helices, and Gly/Ala substitutions (which affect the entropy of the denatured state, and thus its free energy) and increased number of salt bridges. 

TLS Online TPP Program

#Id: 8764

#Unit 1. Structure and Function of Biomolecules

Some thermostable proteins are stabilized by an increased size of the protein’s hydrophobic core, an increased size of the interface between its domains and/or subunits, and a more tightly packed core as evidenced by a reduced surface-to-volume ratio.