Enzymatic treatment of pork protein for the enhancement of iron bioavailability.

The typical intervention for iron-deficiency anaemia is through oral supplementation with iron salts, which have unpleasant side effects. Therefore, there is a need for the development of supplements which will be absorbed more effectively and may have fewer side effects. This study investigated the effects of partially hydrolysed pork proteins on the bioavailability of non-haem iron.

Effects of different proteases on iron absorption property of egg white hydrolysates.

One of the causes of iron deficiency in human is poor absorption of non-heme iron from the diet. While proteins from meats have been reported in the literature to enhance the absorption of non-heme iron, other proteins, such as those from egg, are known to inhibit iron absorption. The objective of this study is to investigate non-heme iron binding property of egg white proteins hydrolyzed using pepsin and a combination of bacterial/fungal proteases.

Conserved prosegment residues stabilize a late-stage folding transition state of pepsin independently of ground states.

The native folding of certain zymogen-derived enzymes is completely dependent upon a prosegment domain to stabilize the folding transition state, thereby catalyzing the folding reaction. Generally little is known about how the prosegment accomplishes this task. It was previously shown that the prosegment catalyzes a late-stage folding transition between a stable misfolded state and the native state of pepsin.

Understanding the mechanism of prosegment-catalyzed folding by solution NMR spectroscopy.

Multidomain protein folding is often more complex than a two-state process, which leads to the spontaneous folding of the native state. Pepsin, a zymogen-derived enzyme, without its prosegment (PS), is irreversibly denatured and folds to a thermodynamically stable, non-native conformation, termed refolded pepsin, which is separated from native pepsin by a large activation barrier. While it is known that PS binds refolded pepsin and catalyzes its conversion to the native form, little structural details are known regarding this conversion.

¹H, ¹³C, and ¹⁵N backbone resonance assignments of the porcine pepsin and porcine pepsin complexed with pepstatin.

Pepsin is formed as the zymogen, pepsinogen, which includes an additional 44 residue prosegment (PS) on the N-terminus. Upon acidification (pH <3) the PS is removed, yielding active pepsin. The PS is critical to such processes as the initiation of correct folding and protein stability.

Crystal structures of the free and inhibited forms of plasmepsin I (PMI) from Plasmodium falciparum.

Plasmepsin I (PMI) is one of the four vacuolar pepsin-like proteases responsible for hemoglobin degradation by the malarial parasite Plasmodium falciparum, and the only one with no crystal structure reported to date. Due to substantial functional redundancy of these enzymes, lack of inhibition of even a single plasmepsin can defeat efforts in creating effective antiparasitic agents. We have now solved crystal structures of the recombinant PMI as apoenzyme and in complex with the potent peptidic inhibitor, KNI-10006, at the resolution of 2.

Rational redesign of porcine pepsinogen containing an antimicrobial peptide.

A novel strategy for the controlled release and localization of bioactive peptides within digestive and immunity-related enzymes was developed. The N-terminus of porcine pepsinogen A was fused to the basic amino acid-rich region of bovine lactoferricin B termed 'tLfcB', a cationic antimicrobial/anticancer peptide. Recombinant tLfcB-porcine pepsinogen A was expressed in soluble form in Escherichia coli as a thioredoxin (Trx) fusion protein.

Recombinant prosegment peptide acts as a folding catalyst and inhibitor of native pepsin.

Porcine pepsin A, a gastric aspartic peptidase, is initially produced as the zymogen pepsinogen that contains an N-terminal, 44 residue prosegment (PS) domain. In the absence of the PS, native pepsin (Np) is irreversibly denatured and when placed under refolding conditions, folds to a thermodynamically stable denatured state. This denatured, refolded pepsin (Rp) state can be converted to Np by the exogenous addition of the PS, which catalyzes the folding of Rp to Np.

Multifunctional aspartic peptidase prosegments.

The structure-function relationships of aspartic peptidases (APs) (EC 3.4.23.