Synthesis of fructans by fructosyltransferase from the tuberous roots of Viguiera discolor (Asteraceae)

Infant food applications of complex carbohydrates: Structure, synthesis, and function

Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

A general method for assaying homo- and hetero-transglycanase activities that act on plant cell-wall polysaccharides

Transglycanases (endotransglycosylases) cleave a polysaccharide (donor-substrate) in mid-chain, and then transfer a portion onto another poly- or oligosaccharide (acceptor-substrate). Such enzymes contribute to plant cell-wall assembly and/or re-structuring. We sought a general method for revealing novel homo- and hetero-transglycanases, applicable to diverse polysaccharides and oligosaccharides, separating transglycanase-generated (3)H-polysaccharides from unreacted (3)H-oligosaccharides--the former immobilized (on filter-paper, silica-gel or glass-fiber), the latter eluted. On filter-paper, certain polysaccharides [e.g. (1→3, 1→4)-β-D-glucans] remained satisfactorily adsorbed when water-washed; others (e.g. pectins) were partially lost. Many oligosaccharides (e.g. arabinan-, galactan-, xyloglucan-based) were successfully eluted in appropriate solvents, but others (e.g. [(3)H]xylohexaitol, [(3)H]mannohexaitol [(3)H]cellohexaitol) remained immobile. On silica-gel, all (3)H-oligosaccharides left an immobile 'ghost' spot (contaminating any (3)H-polysaccharides), which was diminished but not prevented by additives e.g. sucrose or Triton X-100. The best stratum was glass-fiber (GF), onto which the reaction-mixture was dried then washed in 75% ethanol. Washing led to minimal loss or lateral migration of (3)H-polysaccharides if conducted by slow percolation of acidified ethanol. The effectiveness of GF-blotting was well demonstrated for Chara vulgaris trans-β-mannanase. In conclusion, our novel GF-blotting technique efficiently frees transglycanase-generated (3)H-polysaccharides from unreacted (3)H-oligosaccharides, enabling high-throughput screening of multiple postulated transglycanase activities utilising chemically diverse donor- and acceptor-substrates.

Hydrolase and fructosyltransferase activities implicated in the accumulation of different chain size fructans in three Asteraceae species

Fructans are widely distributed in Asteraceae from floras with seasonal growth and are thought to be involved in drought and freezing tolerance, in addition to storage function. Reserve organs of Vernonia herbacea and Viguiera discolor, from the cerrado, and of the perennial herb Smallanthus sonchifolius, endemic to Andean region, store over 80% inulin, with different DP (35, 150, and 15, respectively). The fructan pattern in Asteraceae species could be explained by characteristics of their respective 1-FFTs. Hydrolases and fructosyltransferases from S. sonchifolius, V. herbacea and V. discolor were analyzed in plants at the same environmental conditions. The higher 1-FEH activities found in the species with lower DP, S. sonchifolius and V. herbacea reinforce the hypothesis of the involvement of 1-FEH in fructan profile and suggest that the high DP fructan of V. discolor is a consequence of the low affinity of its 1-FEH to the native long chain inulin. Long term incubation with sucrose suggested that the affinity of 1-FFT of V. discolor for 1-kestose is low when compared to that of V. herbacea. Indeed 1-FFT from V. discolor was shown to be an hDP 1-FFT, preferring longer inulins as acceptors. Conversely, 1-FFT from V. herbacea seems to have a higher affinity for short fructo-oligosaccharides, including 1-kestose, as acceptor substrates. Differences in fructan enzymes of the three Asteraceae provide new information towards the understanding of fructan metabolism and control of carbon flow between low and high DP fructans.