Detection of native protein ions in aqueous solution under ambient conditions by electrospray laser desorption/ionization mass spectrometry.
Liquid electrospray laser desorption/ionization (ELDI) mass spectrometry allows desorption and ionization of proteins directly from aqueous solutions and biological fluids under ambient conditions. Native protein ions such as those of myoglobin, cytochrome c, and hemoglobin were obtained. A droplet (ca. 5 microL) containing the protein molecules and micrometer-sized particles (e.g., carbon graphite powder) is irradiated with a pulsed UV laser. The laser energy adsorbed by the inert particles is transferred to the surrounding solvent and protein molecules, leading to their desorption; the desorbed gaseous molecules are then postionized within an electrospray (ESI) plume to generate the ESI-like protein ions. With the use of this technique, we detected only the protonated protein ions in various biological fluids (including human tears, cow milk, serum, and bacterial extracts) without interference from their corresponding sodiated or potassiated adduct ions. In addition, we rapidly quantified the levels of glycosylated hemoglobin present in drops of whole blood obtained from diabetic patients without the need of sample pretreatment.
Shiea
Jentaie
J
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan. jetea@mail.nsysu.edu.tw
Yuan
Cheng-Hui
CH
Huang
Min-Zong
MZ
Cheng
Sy-Chyi
SC
Ma
Ya-Lin
YL
Tseng
Wei-Lung
WL
Chang
Hui-Chiu
HC
Hung
Wen-Chun
WC
D000818:Animals; D002417:Cattle; D045304:Cytochromes c / Q000032:analysis; D029968:Escherichia coli Proteins / Q000032:analysis; D006442:Glycated Hemoglobin / Q000032:analysis; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000032:analysis; D008892:Milk / Q000737:chemistry; D009113:Muramidase / Q000032:analysis; D009211:Myoglobin / Q000032:analysis; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet; D013666:Tears / Q000737:chemistry; D014867:Water / Q000737:chemistry
D045304:Cytochromes c; D029968:Escherichia coli Proteins; D006442:Glycated Hemoglobin; D006454:Hemoglobins; D007328:Insulin; D009113:Muramidase; D009211:Myoglobin; D011506:Proteins; D012996:Solutions; D014867:Water