| Author | Message | ||
     Larry Kollasch (larry_kollasch) New member Username: larry_kollasch Post Number: 1 Registered: 8-2010 |
All, As part of her independent research, my daughter is interested to measure Trypsin inhibitor to compare GM with organic soya products. What kinds of lab tests should she consider? Thanks for your advice, Larry Kollasch | ||
| Gabi Levin (gabiruth) Intermediate Member Username: gabiruth Post Number: 17 Registered: 5-2009 |
Hi, The more I read about it - the more I am convinced that unless some one can tell us what is the actual concentration of the trypsin and the inhibitor we will be dancing around. Once we know that we will be in better position to tell if NIR can be used for direct determination of the inhibitor's activity. Assuming it is very low, the procedure I suggested, run a two fold test under exactly same conditions, with and without the inhibitor, and measure the rate of formation of the enzymatic proteolysis products. Where there is little or no inhibitor, expect high rate of formation, where there is high inhibitor activity, the rate of formation of products shall be very low. Gabi Levin | ||
| Dennis Karl (dennisk) Member Username: dennisk Post Number: 13 Registered: 4-2004 |
Sorry David - re my last posting. I should have read the subject line!!! | ||
| Dennis Karl (dennisk) Member Username: dennisk Post Number: 12 Registered: 4-2004 |
Hi David, You have not stated what product your customer wants to measure typsin inhibition in. Soy beans have this inhibitor but, because the testing for it is tedious and impractical for day to day quality monitoring of soya meal after oil extraction, urease activity is measured instead. Urease activity is relatively easy to measure. Our lab has managed to develop a calibration equation to measure urease activity that is fit for our purpose. The challenge is to get commercial soya meal with urease activity sufficient to cover a wide enough concentration range. Our calibration gives us values which are indicators of levels of activity which closely match the uncertainty of the AOCS method. It is a good enough screening tool to tell us if the meal we are testing is meeting our specification or not. What "chemistry" we are actually measuring - goodness knows - but it works for us!!!!!! | ||
| David von Boisman (david_von_boisman) Member Username: david_von_boisman Post Number: 14 Registered: 2-2006 |
Well, There are a lot of people using NIR for industrial applications that has little or no foundation in science - ash in agricultural products being such an example. In these cases we look at secondary correlations that are not always easy to understand or rationalize. Looking at enzyme activity in particular, many people have tried that in wheat flour using Falling Number as the reference method (alfa-amylase activity), those attempts has almost universally failed. I hoped it to be different in Soy products for a number of reasons, thats why I ask if somebody have tried. | ||
| Gabi Levin (gabiruth) Intermediate Member Username: gabiruth Post Number: 16 Registered: 5-2009 |
David, This is very interesting - people are still regarding NIR as some magic box - before we even consider the actual issue - we need to uderstand the nature of the chemistry involved - if I understand correctly there is an enzyme called trypsin (see Wikipedia, this one is very common enzyme used in biotech for breaking proteins down) and there is some inhibitor that suppresses its activity to slow it down or stop it completely. I would imagine that the concentration of the enzyme (which by itself is probably short chain protein) is very low to begin with and the concentration of the inhibitor is equally low or maybe even lower. If these are really low in the micrograms per liter,then the only way to measure the activity of the inhibitor is to run two identical sets of tests - one with the trypsin but no inhibitor, same pH, same temp. same evrything else, and one with the inhibitor and follow the rate of increase in the products of the proteolysis effected by the trypsin in the one without inhibitor as compared to the one with the inhibitor. This would be quite complicated, will require substantial set ups and will be prone to various errors. NIR could possibly be used to monitor the products of the proteolysis - say by folllowing specific amino acid levels as function of time. Still - this will be very complex and will require substantial calibration work by analysis of the proteolysis products by other methods and then correlate to NIR. In that sense, NIR will be used as an indirect method to circumvent the other difficulties. I hope it makes sense to you guys. Gabi Levin | ||
| Manoj Dinesh Oak (manojoak) New member Username: manojoak Post Number: 3 Registered: 7-2007 |
Hi, I would appreciate to receive answers, references or reports, if anybody have the solution for Dr. david von boisman question trypsin inhibitor content estimation using NIR from soybean. | ||
| Manoj Dinesh Oak (manojoak) New member Username: manojoak Post Number: 2 Registered: 7-2007 |
I scanned around 56 durum wheats from India, in this set few are red grain ones and few are yellow grain ones, 35 durum wheats are old varieties, they have different seed shape and size. I want to identify new and old varieties from NIT spectrum, how can detect the wavelength which one is useful for this kind of study. with best regards Manoj Oak | ||
| David von Boisman (david_von_boisman) Member Username: david_von_boisman Post Number: 13 Registered: 2-2006 |
Hi, A customer, currently using a NIRSystems 6500, asked me if they can use this instrument to measure Trypsin inhibitor activity. Would be easy to test if they had the reference method established in their lab, but that is not the case. Do anybody have experience in this, or can you link to a reference or a report? Best regards David von Boisman |