Analysis of picogram quantities of protein in subnanoliter-size samples

✍ Scribed by David Zawieja; B.J. Barber; Richard J. Roman

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 549 KB
• Volume: 142
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(84)90535-9

✦ Synopsis

The ability to measure protein concentration in subnanoliter volumes would be helpful in many biological studies. A microassa y for measuring nanogram protein quantities in nanolitersize samples and an ultramicroassa y for measuring picogram quantities in picoliter samples were developed to measure lymphatic protein concentration. Aliquots of a sample solution were mixed with an o-phthalaldehyde mercaptoethanol reagent using micropipetting techniques.

Reaction product tluorescence was measured using a modified Leitz MPV-I microscope as a microtluorometer. Ruorescence varied linearly with albumin concentrations between 1 and 8 g/100 ml. A typical microassa y measuring albumin standards at 0.0, 1.0, 2.0, and 4.0 g/100 ml yielded a linear regression of y = 207x + 60 (r = 0.99). Minimum detectable protein concentration was 0.125 g/ 100 ml. The SE for the albumin standards varied from 0.02 to 0.17 g/100 ml. An ultramicroamay measuring similar standards yielded a linear regression of y = 1180x + 109 (r = 0.96). Minimum detectable protein concentration was 0.028 g/100 ml.

The SE for the standards varied from 0.01 to 0.32 g/100 ml. 0 1984 Academic ~esr. hc.