A novel informatics concept for high-throughput shotgun lipidomics based on the molecular fragmentation query language

Table 4 Benchmarking LipidXplorer identification performance using the E. coli lipidome

Lipid class	Reference list	LipidMaps^a	LipidQA^b	LipidSearch	LipidXplorer
True positives
PA^c	0	0	0/1	0/1	0/0
PE	21	18	12/14	14/21	21/27
PG	15	10	8/13	9/17	15/25
Compliance^d, %			56	64	100
False positives
PS			2	0	0
PI			0	0	0
PUFA species^e			7	2	1
Total			9	2	1

^aThe lipid species database is at [53]. ^bThe number of identified species is presented as 'Number of species that belong to the reference list/Total number of identified species'. The numbers are presented separately for each class. ^cPA is a very minor (<0.01 mol%) component of the E. coli lipidome. ^dCompliance is a ratio of the total number of identified species that belong to the reference list to the total number of identified species. It is calculated for species of all three lipid classes together. ^ePutative lipid species with polyunsaturated fatty acids (PUFAs) were searched within PA, PE and PG lipid classes. With respect to PUFAs here, we assumed fatty acids having more than two double bonds to account even for the rarest instances when a moiety might contain one double bond and one cyclopropane ring.

ISSN: 1474-760X