title: Biochemical modifications of gliadins induced by microbial transglutaminase on wheat flour.
abstract: BACKGROUND
  Celiac disease (CD) is an immune-mediated disorder caused by the ingestion of wheat gluten. A lifelong, gluten-free diet is required to normalize the intestinal mucosa. We previously found that transamidation by microbial transglutaminase (mTGase) suppressed the gliadin-specific immune response in intestinal T-cell lines from CD patients and in models of gluten sensitivity.
  
  
  METHODS
  SDS-PAGE, Western blot, ELISA, tissue transglutaminase (tTGase) assay and nano-HPLC-ESI-MS/MS experiments were used to analyze prolamins isolated from treated wheat flour.
  
  
  RESULTS
  Gliadin and glutenin yields decreased to 7.6±0.5% and 7.5±0.3%, respectively, after a two-step transamidation reaction that produced a water-soluble protein fraction (spf). SDS-PAGE, Western blot and ELISA analyses confirmed the loss of immune cross-reactivity with anti-native gliadin antibodies in residual transamidated gliadins (K-gliadins) and spf as well as the occurrence of neo-epitopes. Nano-HPLC-ESI-MS/MS experiments identified some native and transamidated forms of celiacogenic peptides including p31-49 and confirmed that mTGase had similar stereo-specificity of tTGase. Those peptides resulted to be 100% and 57% modified in spf and K-gliadins, respectively. In particular, following transamidation p31-49 lost its ability to increase tTGase activity in Caco-2 cells. Finally, bread manufactured with transamidated flour had only minor changes in baking characteristics.
  
  
  CONCLUSIONS
  The two-step transamidation reaction modified the analyzed gliadin peptides, which are known to trigger CD, without influencing main technological properties.
  
  
  CONCLUSIONS
  Our data shed further light on a detoxification strategy alternative to the gluten free diet and may have important implications for the management of CD patients.
authors.affiliation: Institute of Food Sciences, CNR, Avellino, Italy.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Mazzeo
authors.forename: Roberta
authors.initials: R
authors.lastname: Bonavita
authors.forename: Francesco
authors.initials: F
authors.lastname: Maurano
authors.forename: Paolo
authors.initials: P
authors.lastname: Bergamo
authors.forename: Rosa A
authors.initials: RA
authors.lastname: Siciliano
authors.forename: Mauro
authors.initials: M
authors.lastname: Rossi
mesh_terms: D000595:Amino Acid Sequence; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D005433:Flour; D005903:Gliadin / Q000737:chemistry / Q000378:metabolism*; D005983:Glutens / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D011503:Transglutaminases / Q000737:chemistry / Q000378:metabolism*; D014908:Triticum / Q000378:metabolism*
chemical_list: D010455:Peptides; D005983:Glutens; D005903:Gliadin; D011503:Transglutaminases; C037302:glutenin
keywords: CD; Celiac disease; GFD; Gliadin; K-C(2)H(5); K-gliadins; Microbial transglutaminase; PEPs; Transamidation; gluten-free diet; insoluble transamidated gliadin; lysine ethyl ester; mTGase; microbial transglutaminase; nano-HPLC–ESI-MS/MS; prolyl endopeptidases; spf; tTGase; tandem mass spectrometry coupled with nano-reverse phase liquid chromatography; tissue transglutaminase; water-soluble protein fraction