We investigated the possible side chain/side chain interactions of four potential transmembrane proteins. The basic assumptions are that the proteins are alpha-helical, and that the proteins aggregate with knobs-into-holes packing. It was found that these four proteins can be assembled into stereochemically feasible bundles of alpha-helices with hydrophobic exteriors and with hydrogen bonds between the side chains of one alpha-helix and the side chains of its knobs-into-holes packed neighbors.

Reaction of Pd(OzCMe)2 with PhCH2NHz leads to either Pd(NH2CH2Ph)2(02CMe)2 or [Pd(NH2CH2Ph)4] [02CMe],. The X-ray crystal structure of [Pd(NHZCH2Ph),] [Cl] [02CMe] shows pairs of [Pd (NH2CH2Ph),12 + ions held together by hydrogen bonds from the NH proton to chlorine and oxygen atoms of the anions, and the absence of interactions between phenyl ring ortho protons and the metal. PhCH2NHMe reacts with Pd(02CMe)2 giving Pd(NHMeCH2Ph)2(OZCMe) and PhCHzNMe2 gives the cyclometallate [Pd(NMe2CH2Ph-C,N)(p-OzCMe)]2. 'H n.m.r. spectra indicate that the complexes Pd(NMezCH2Ph)(L)(02CMe)z (L = PhNH2, o-MeC6H4NHz) prepared from [Pd(L)(02CMe)(p-02CMe)12, contain an interaction of the benzylamine ortho aromatic protons with the metal whereas Pd(NHMeCHzPh)(L)(02CMe)z (L = o-MeC,H4NH2) does not. 'H n.m.r. analysis of PdC142-and PhCH2NMe2 in (2Hl)methanol at 400 MHz indicates a 1 : 1 reaction stoichiometry and metal-proton interactions in intermediates containing above-plane and in-plane geometry of the aromatic ring, before metallation takes place. A 400-MHz spectral analysis of Pd(02CMe), and PhCH2NMe2 in CDC1, suggests similarly orientated species arise in the reaction giving [Pd(NMezCHzPh-C,N)(p-OzCMe)]2.See for example Thompson,