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Colgrave ML, Byrne K, Caine J, Kowalczyk L, Vibhakaran Pillai S, Dong B, Lovrecz G, MacIntosh S, Scoble JA, Petrie JR, Singh S, Zhou XR. Proteomics reveals the in vitro protein digestibility of seven transmembrane enzymes from the docosahexaenoic acid biosynthesis pathway. Food Chem Toxicol 2019; 130:89-98. [PMID: 31085220 DOI: 10.1016/j.fct.2019.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 05/08/2019] [Accepted: 05/10/2019] [Indexed: 11/29/2022]
Abstract
The measurement of protein digestibility is one of the key steps in determining the safety of a genetically modified crop that has been traditionally accomplished using antibodies. Membrane proteins are often extremely difficult to express with replicated authentic tertiary structure in heterologous systems. As a result raising antibodies for use in safety assessment may not be feasible. In this study, LC-MS based proteomics was used to characterise seven transmembrane enzymes from the docosahexaenoic acid biosynthetic pathway that had been introduced into canola. The application of a two-stage digestion strategy involving simulated gastric fluid followed by trypsin enabled the measurement of protein digestibility in vitro. Tryptic peptide markers that spanned the length of each desaturase protein were monitored and showed that these proteins were readily degraded (>95% within 5 min) and highlighted regions of the elongase enzymes that showed limited resistance to simulated gastric digestion. Traditional gel-based and Western blotting analysis of ω3-desaturase and Δ6-elongase revealed rapid hydrolysis of the intact proteins within seconds and no fragments (>3 kDa) remained after 60 min, complementing the novel approach described herein. The LC-MS approach was sensitive, selective and did not require the use of purified proteins.
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Affiliation(s)
| | - Keren Byrne
- CSIRO Agriculture and Food, 306 Carmody Rd, St Lucia, QLD, 4067, Australia
| | - Joanne Caine
- CSIRO Manufacturing, 343 Royal Parade, Parkville, VIC, 3052, Australia
| | - Lukasz Kowalczyk
- CSIRO Manufacturing, 343 Royal Parade, Parkville, VIC, 3052, Australia
| | | | - Bei Dong
- CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - George Lovrecz
- CSIRO Manufacturing, 343 Royal Parade, Parkville, VIC, 3052, Australia
| | - Susan MacIntosh
- Nuseed Americas, 11901 S. Austin Avenue, Alsip, IL, 60803, USA
| | - Judith A Scoble
- CSIRO Manufacturing, 343 Royal Parade, Parkville, VIC, 3052, Australia
| | - James R Petrie
- CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - Surinder Singh
- CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT, 2601, Australia
| | - Xue-Rong Zhou
- CSIRO Agriculture and Food, GPO Box 1700, Canberra, ACT, 2601, Australia
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