HYDROGEN BONDING 81 



Professor Sutherland (University of Michigan): I would like to ask about 

 polyglycines and the letter from Bamford & co-workers (1955) in which they 

 suggest that polyglycine is a 2.27 helix. 



Professor Donohue: I heard about his letter only last night; Nature comes 

 to our library much later than it ought to, so that I have no knowledge of this 

 at all. If it turns out that polyglycine is one of these structures described pre- 

 viously, of course I will be very pleased. 



(A different structure for polyglycine has now been proposed by Crick and 

 Rich (1955). They stated that their structure was in "good qualitative agree- 

 ment" with the X-ray data, but as they chose not to publish the results of the 

 calculations they made on their structure, it is impossible for anyone else to 

 arrive at a conclusion concerning its validity.) 



Chairman Pauling: I would like to comment on Professor Donohue's paper. 

 I think that in the spirit of the true investigator he has concentrated on pre- 

 senting a number of new ideas and discussing some doubtful points in this talk 

 about the hydrogen bond and has not presented a great mass of crystallo- 

 graphic data on substances in which hydrogen bonds are very well behaved and 

 in which there is no doubt about the interpretation of the crystallographic 

 data. Would you tell me if you agree with this? 



Professor Donohue: I would say that some of these substances we have 

 talked about this afternoon weren't very well behaved. Glycine is one I still do 

 not like. 



Chairman Pauling: No, and sulfamic acid is questionable. Would you agree 

 that there are a great number of hydrogen bonded crystals in which there is no 

 doubt about the hydrogen bonds? The environment corresponds nicely to that 

 expected. 



Professor Donohue: Yes; I agree perfectly. In these many complicated 

 substances, some of which we did not look at, you find everything is just lovely. 

 This is why, when you see something where it is not so lovely, you should be 

 exceedingly suspicious. There are dozens of substances that we could not worry 

 about this afternoon where everything fits your preconceived ideas in a perfect 

 way. 



Chairman Pauling: I think it is astounding that a complex molecule such 

 as that of threonine, which has four hydrogen atoms that are sticking out in 

 various directions, is able to find a way of packing together with its equivalent 

 fellows that corresponds to standard density, that is, no holes, each atom occu- 

 pying its place, and still it brings an atom that can interact with the OH hy- 

 drogen atom in such a way as to correspond to the formation of a hydrogen 

 bond. I think it need not surprise us that sometimes the molecule seems to find 

 it impossible to do this perfectly, that sometimes the hydrogen bond is bent 

 by 10 or 15 or 20 degrees, and that sometimes the distance is not to the 2.80 

 that one might expect but is 3.06 A. 



