Dipole and size of a thioether relative to hydrocarbon
I just realised that I got the dipole business utterly wrong as sulfur has two lone pairs.
I checked dimethyl sulfide, propane and dimethyl ether and was surprised how differently they behaved. The former has a total dipole moment of 1.5 D ref, while the second near zero (0.1 D) as expected from a non-polar molecule, while the last has 1.3 D.
Whereas there is only a 0.03 difference in electronegativity between C and S (vs. .89), the geometry is different, which I did not know about. Wikipedia on says:


thioether article: "C–S–C angle approaching 90°. The C–S bonds are about 180 pm."
ether article: "C–O–C linkage defined by a bond angle of about 110° and C–O distances of about 140 pm".
alkane article: "154 [pm] for a C–C bond [and] with an angle of 109.47° between them."


So the side chain of methionine should actually be able to hydrogen bond with stuff (not electrostatically, but dispersively). So I was surprised to find papers I had not found prior (ex1, ex2).

S-&pi; are probably the strongest force nevertheless (the bond has an enthalpy of 2.6, 1.1 or 0.7 kcal mol-1 depending on the angleref, which is comparable to N−H···:O hydrogen bond (1.9 kcal mol-1))