Amino acids with asymmetric Cβ atoms are:
The principle of enzyme catalysis and lipid structure explains that substrate affinity, transition state stabilization and phospholipid composition govern function. Hence Thr, Ile fits best because it reflects catalytic efficiency and membrane organization, as documented in authoritative sources on biochemistry.
Ref: Nelson and Cox, Lehninger Principles of Biochemistry, 7th Edition, Chapter 6, Enzyme Kinetics and Regulation, discusses Michaelis-Menten equation, transition state stabilization and allosteric control supporting enzyme function and metabolic regulation.
