Investigation of mitochondrial protein expression profiles of Yarrowia lipolytica in response to citric acid production.

Nitrogen-limiting condition is essential for citric acid production by Yarrowia lipolytica. Mitochondrial protein expression profiles of Y. lipolytica IMUFRJ 50,682 cells cultivated in biomass proliferation medium (YPG medium, yeast extract, peptone and glycerol) and citric acid production medium (CA medium) were analyzed to identify differences in expressed proteins in response to medium composition. The identification of 45 proteins in mitochondria of YPG medium cells and 48 proteins in mitochondria of CA medium cells were possible with proteomic analyses. Only 11 proteins were common to both conditions, showing a different expression pattern in relation to limiting and non-limiting nitrogen conditions. For both conditions, most proteins (52%-CA medium, 46%-YPG medium) were related to energy metabolism. CA medium cells expressed more carbohydrate metabolism proteins (six proteins) then YPG medium cells (three proteins) and the opposite was detected for translation proteins.

Protective factors in mature human milk: a look into the proteome and peptidome of adolescent mothers' breast milk.

The characterisation of proteome and peptidome of adolescent mothers' breast milk brings important information to both mother's and infant's health; however, it has not been investigated. Bioactive peptides derived from milk proteins have numerous functions. The bioactivity of breast milk peptides includes anti-inflammatory and antimicrobial activities and regulation of gastrointestinal function. We aimed to characterise the proteome and peptidome of mature breast milk of adolescent mothers and investigate whether it is affected by lactational period. We used a combination of electrophoretic and nano-scale LC-quadrupole time-of-flight MS/MS (nLC-Q-TOF-MS/MS) techniques and bioinformatics to explore the proteome of human skimmed milk expressed by lactating adolescents in two groups according to postpartum period (up to 3 and over 5 weeks postpartum). This is the first study that analysed the proteome of adolescent mothers' breast milk produced during two periods of lactation using 1D-electrophoresis combined with nLC-Q-TOF-MS/MS analysis. Our results showed that the protein composition of adolescent milk varies independently of lactation stage and showed high inter-individual variation. A total of 424 proteins were identified in skimmed milk, of which 137 proteins were common to both groups. Most of the peptides found in adolescents' breast milk were not derived from major proteins in milk. Association maps showed several interactions between groups of peptides that pointed to the relevance of breast milk peptides to neonatal defensive system.