What it is
Endotoxin is lipopolysaccharide from the outer membrane of Gram-negative bacteria. It is released when cells lyse, and it is heat-stable — ordinary sterilisation does not remove it.
Why production route decides relevance
A protein expressed in E. coli is purified from a bacterial lysate, so endotoxin is a plausible carry-over and is tested for. A chemically synthesised tripeptide never met a bacterium, so the test would be answering a question that does not arise.
Seeing endotoxin data on one certificate and not another is therefore usually appropriate rather than a gap.
What a result describes
Results are reported in endotoxin units per milligram and describe the batch tested. Like every other figure on a certificate, it is batch-specific and says nothing about a different lot.
Research use only. This page is explanatory and does not recommend any use, quantity or procedure. REVIVE LAB supplies reference materials for laboratory research. These are not medicines and are not for human or veterinary consumption. Anyone considering the use of any compound in humans should do so only under qualified medical supervision.