How do you know that DPP IV is really in a product?

Devin Houston, Ph.D.

Question: I'm confused by some of the labels I see on some enzyme products. For example, some products claim to have DPP IV in them but I don't see it on the ingredients. How do I know that DPP IV is really in the product?

Answer: Excellent question. It basically comes down to what is considered a standard enzyme, and how its activity can be measured.

DPP IV ("DPP 4") is the acronym for the enzyme Dipeptidyl Peptidase IV. Early DPP IV-containing products did not list DPP IV in the ingredients box because there was no standardized assay by which to quantitate the enzyme. Also, DPP IV was considered a "contaminating" activity, or "side activity" in certain protease enzymes. All enzymes contain some amount of other enzymes, and that is the case with DPP IV. It was not known to be present in the commercially available proteases until we actually looked for it in 1999.

I fashioned an assay to detect DPP IV and determined that DPP IV was present in several protease enzymes and very high in a peptidase enzyme blend. Peptidase activity is measured in units called HUT. But because the DPP IV assay was not well-known, enzyme companies simply stated DPP IV as a measure of peptidase activity HUT units. So, it was assumed that higher peptidase activity correlated with higher DPP IV levels.

Now however, some enzyme companies have "standardized" the DPP IV assay such that we can confidently state the actual DPP IV units on the label. Remember, if a number is stated in the ingredients label, FDA mandates that it be accurate.

We at Houston Enzymes now state actual DPP IV activity units on our TriEnza product separate from protease and peptidase units. We are also in the process of changing labels for Peptizyde and AFP Peptizyde to reflect the amount of DPP IV present. This is important because not all peptidase enzymes will contain DPP IV.

Bottom line: To be assured that you are getting DPP IV, look for the actual DPP IV activity unit (DPPU) in the ingredient label.