Amino Acids: Proline

PROLINE PRO, P

CHEMICAL STRUCTURE

CHEMICAL SHIFTS

Standard chemical shifts of random extended chain structures:

¹H^a (trans)	¹³C^a(trans)	¹³C^a(cis)	¹⁵N^b
HA: 4.44 HB: 2.28, 2.02 HG: 2.03 HD: 3.68, 3.65	CO: 175.2 CA: 61.6 CB: 30.6 CG: 25.5 CD: 48.2	CO: 175.2 CA: 61.3 CB: 33.1 CG: 23.2 CD: 48.8	N: 128.1

a) from 86BOOK1: b) from 91JMB311-222

More info in:

¹H chemical shifts of amino acids

¹³C chemical shifts of amino acids

Average ¹HA, ¹HN and ¹⁵N chemical shifts in random coil

IDENTIFICATION

Easy spin system identification from:

HA-HB cross-peak in a COSY-DQF experiment.

SECONDARY STRUCTURE

Standard average chemical shift values used in determination of secondary structure by means of the CSI method:
HA: 4.44
CA: 63.0
CO: 176.0
Thus:
          HELIX           B STRAND          COIL
             CA      CO       CA      CO           CA      CO
            65.9    179.5     62.5    174.8      63.3    176.0
More info in: ¹³CA and ¹³CO chemical shifts according to secondary structure.

OBSERVATIONS

NMR studies on cis-trans isomerization (90BIO4400)
NOE peaks between proline and its preceding residue, X, can be utilized to distinguish between cis- and trans-X-Pro peptide bonds taking in account:

Trans X-Pro shows strong NOEs between the two HD(PRO) and HA(X) and between the two HD(PRO) and NH(X).

Cis X-Pro shows strong NOEs between the two HA(PRO) and HA(X) and between the two HA(PRO) and NH(X).

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