Matrix assisted laser desorption ionization mass spectrometry imaging identifies markers of ageing and osteoarthritic cartilage

Table 1 Proteins identified from MS/MS profiling and targeted MS experiments of cartilage

Accession	Protein	Observed mass	Score from profiling MS	Score from targeted MSMS	Peptide	Identified targeted MS studies
O18832_HORSE	Aggrecan	2,325.3		43	R.VSLPNYPAIPTDATLELQNLR.S	✓
PGS1_HORSE	Biglycan	1,312.8	41	43	K.IQAIELEDLLR.Y	✓
PGS1_HORSE	Biglycan	2,027.2		47	K.NHLVEIPPNLPSSLVELR.V	✓
CILP2_HORSE	Cartilage intermediate layer protein	2,196.2	96	67	R.FLPSEQIQGVVVSAINLEPR.A	✓
COMP_HORSE	Cartilage oligomeric matrix protein	1,698.9	31		K.QMEQTYWQANPFR.A
COMP_HORSE	Cartilage oligomeric matrix protein	2,256.1		86	R.FYEGPELVADSNVVLDTTMR.G^a	✓
CHAD_BOVIN	Chondroadherin	2,198.3	17		R.AGAFDDLTELTYLYLDHNK.V	✓
CO2A1_MOUSE	Collagen alpha-1(II) chain	1,679.9	39	75	K.DGETGAAGPPGPSGPAGER.G	✓
CO2A1_HORSE	Collagen alpha-1(II) chain	1,427.9	23		K.ALLIQGSNDVEIR.A
CL-43_BOVINE	Collectin 43	2,415.0		33	K.GEPGPEGGVGAPGMPGSPGPAGLKGER.G	✓
FMOD_BOVIN	Fibromodulin	1,557.0	67	42	R.SLILLDLSYNHLR.K	✓
FMOD_BOVIN	Fibromodulin	1,955.2	67	74	K.IPPVNTNLENLYLQGNR.I^a	✓
FINC_HORSE	Fibronectin	1,401.7		68	K.HYQINQQWER.T^a	✓
HBBA_HORSE	Hemoglobin subunit beta-A	1,274.9	23		R.LLVVYPWTQR.F
MATN3_HORSE	Matrilin-3	1,618.0	20		K.SRPLDLVFIIDSSR.S
MIA3_MOUSE	Melanoma inhibitory activity 3	1,186.7	24		R.EYAPGVLPGKR.D

The proteins identified following profiling and targeted MS studies from cartilage are represented. The table identifies the Swissprot accession number, abbreviation of the protein name, experimental molecular weight of the matched peptides, the score given by the Mascot algorithm and the sequence of the matched peptides. All Mascot scores were significant (P <0.05). All peptide sequences were checked against the equine sequence and were homologous. ^adenotes peptides previously identified in a human cartilage MALDI-IMS study [9]. MS, mass spectrometry; MS/MS, tandem mass spectroscopy.

ISSN: 1478-6362