select polar1, 4J3C&resn Arg+Lys+Asp+Glu+Asn+Gln+His+Tyr+Thr+Ser+Gly
select polar2, sym*&resn Arg+Lys+Asp+Glu+Asn+Gln+His+Tyr+Thr+Ser+Gly

select set1, byres (polar1 and (polar2 around 3.5))
select set2, byres (polar2 and (polar1 around 3.5))
dist hbonds1, set1, set2, 3.5