TY - JOUR
T1 - Structural elucidation of diglycosyl diacylglycerol and monoglycosyl diacylglycerol from Streptococcus pneumoniae by multiple-stage linear ion-trap mass spectrometry with electrospray ionization
AU - Tatituri, Raju Venkata Veera
AU - Brenner, Michael B.
AU - Turk, John
AU - Hsu, Fong Fu
PY - 2012/1
Y1 - 2012/1
N2 - The cell wall of the pathogenic bacterium Streptococcus pneumoniae contains glucopyranosyl diacylglycerol (GlcDAG) and galactoglucopyranosyldiacylglycerol (GalGlcDAG). The specific GlcDAG consisting of vaccenic acid substituent at sn-2 was recently identified as another glycolipid antigen family recognized by invariant natural killer T-cells. Here, we describe a linear ion-trap multiple-stage (MS n) mass spectrometric approach towards structural analysis of GalGlcDAG and GlcDAG. Structural information derived from MS n (n = 2, 3) on the [M + Li] + adduct ions desorbed by electrospray ionization affords identification of the fatty acid substituents, assignment of the fatty acyl groups on the glycerol backbone, as well as the location of double bond along the fatty acyl chain. The identification of the fatty acyl groups and determination of their regio-specificity were confirmed by MS n (n = 2, 3) on the [M + NH 4] + ions. We establish the structures of GalGlcDAG and GlcDAG isolated from S. pneumoniae, in which the major species consists of a 16:1- or 18:1-fatty acid substituent mainly at sn-2, and the double bond of the fatty acid is located at ω-7 (n-7). More than one isomers were found for each mass in the family. This mass spectrometric approach provides a simple method to achieve structure identification of this important lipid family that would be very difficult to define using the traditional method.
AB - The cell wall of the pathogenic bacterium Streptococcus pneumoniae contains glucopyranosyl diacylglycerol (GlcDAG) and galactoglucopyranosyldiacylglycerol (GalGlcDAG). The specific GlcDAG consisting of vaccenic acid substituent at sn-2 was recently identified as another glycolipid antigen family recognized by invariant natural killer T-cells. Here, we describe a linear ion-trap multiple-stage (MS n) mass spectrometric approach towards structural analysis of GalGlcDAG and GlcDAG. Structural information derived from MS n (n = 2, 3) on the [M + Li] + adduct ions desorbed by electrospray ionization affords identification of the fatty acid substituents, assignment of the fatty acyl groups on the glycerol backbone, as well as the location of double bond along the fatty acyl chain. The identification of the fatty acyl groups and determination of their regio-specificity were confirmed by MS n (n = 2, 3) on the [M + NH 4] + ions. We establish the structures of GalGlcDAG and GlcDAG isolated from S. pneumoniae, in which the major species consists of a 16:1- or 18:1-fatty acid substituent mainly at sn-2, and the double bond of the fatty acid is located at ω-7 (n-7). More than one isomers were found for each mass in the family. This mass spectrometric approach provides a simple method to achieve structure identification of this important lipid family that would be very difficult to define using the traditional method.
KW - ESI
KW - diglycosyl diacylglycerol
KW - glycolipids
KW - ion-trap mass spectrometry
KW - lithium adduct ion
KW - monoglycosyl diacylglycerol
KW - streptococcus pneumoniae
UR - http://www.scopus.com/inward/record.url?scp=84856352587&partnerID=8YFLogxK
U2 - 10.1002/jms.2033
DO - 10.1002/jms.2033
M3 - Article
C2 - 22282097
AN - SCOPUS:84856352587
SN - 1076-5174
VL - 47
SP - 115
EP - 123
JO - Journal of Mass Spectrometry
JF - Journal of Mass Spectrometry
IS - 1
ER -