A stability study of the esterase D isoenzymes

Area of Science:

• Forensic science
• Biochemistry
• Genetics

Background:

• Erythrocyte pyrophosphatase (EsD) is an enzyme found in red blood cells.
• EsD exhibits genetic polymorphism, with different phenotypes like EsD 1 and 2--1.
• Understanding the stability of EsD isoenzymes is crucial for forensic analysis of bloodstains.

Purpose of the Study:

• To investigate the stability of EsD isoenzymes in aging bloodstains.
• To establish criteria for interpreting electrophoretic patterns of EsD in aged samples.
• To determine the influence of storage conditions (temperature, anticoagulants) on EsD stability.

Main Methods:

• Electrophoretic analysis of EsD phenotypes in bloodstains of varying ages.
• Comparative study of EsD stability in fluid blood under different storage conditions (3°C, room temperature, 37°C).
• Assessment of anticoagulant effects (heparin, oxalate, EDTA, citrate-fluoride) on EsD degradation.

Main Results:

• Established criteria for interpreting EsD patterns in aged bloodstains.
• EsD isoenzymes in dried bloodstains showed maximum stability of four weeks.
• In fluid blood, degradation at 37°C was complete within three days.
• At 3°C, instability was observed after six weeks, unaffected by anticoagulant type.
• Room temperature storage with anticoagulants/preservatives did not enhance EsD stability.
• EDTA significantly accelerated degradation in fluid blood, reducing stability to three days.

Conclusions:

• Dried bloodstains offer a limited window of four weeks for reliable EsD analysis.
• Storage temperature and specific anticoagulants critically impact EsD stability in fluid blood.
• EDTA is detrimental to EsD stability, posing challenges for forensic casework involving EDTA-treated samples.