{"id":18399,"date":"2017-05-29T18:31:49","date_gmt":"2017-05-29T17:31:49","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=18399"},"modified":"2017-05-29T18:31:49","modified_gmt":"2017-05-29T17:31:49","slug":"ch%e2%8b%85%e2%8b%85%e2%8b%85%cf%80-interactions-between-methyl-and-carbonyl-groups-in-proteins-a-small-molecule-check","status":"publish","type":"post","link":"https:\/\/www.rzepa.net\/blog\/?p=18399","title":{"rendered":"CH\u22c5\u22c5\u22c5\u03c0 Interactions between methyl and carbonyl groups in proteins: a small molecule check."},"content":{"rendered":"
\n

Derek Lowe<\/a> highlights a recent article[1]<\/a><\/span> postulating\u00a0CH\u22c5\u22c5\u22c5\u03c0 interactions in proteins. Here I report a quick check using the small molecule crystal structure database (CSD).<\/p>\n

The search query (DOI:\u00a010.14469\/hpc\/2594<\/a>)\u00a0is shown below.\"\"<\/p>\n

    \n
  1. The distance refers to that between the (normalised) position of a hydrogen on a 4-coordinated carbon atom and the centroid of a carbonyl group substituted with R=C or H.\u00a0<\/li>\n
  2. The angle is that subtended at the centroid. An approach orthogonal to the axis of the carbonyl group will have a value of 1.0 for the sine.<\/li>\n
  3. The torsion relates to the angle between the H…centroid and C-R vectors. The absolute value is constrained to 70-110\u00b0 to filter only approaches towards the \u03c0-system of the carbonyl.<\/li>\n
  4. The search is further restricted to no disorder, no errors and R < 0.05.\u00a0<\/li>\n<\/ol>\n

    \"\"<\/p>\n

    The two most interesting hits, both revealing short distances and ~orthogonal approaches to the\u00a0\u03c0-system are:<\/p>\n