Alpha 1 -antitrypsin is the most abundant circulating protease inhibitor. The severe Z deficiency allele (Glu342Lys) causes the protein to undergo a conformational transition and form ordered polymers that are retained within hepatocytes. This causes neonatal hepatitis, cirrhosis, and hepatocellular carcinoma. We have developed a conformation-specific monoclonal antibody (2C1) that recognizes the pathological polymers formed by a 1 -antitrypsin. This antibody was used to characterize the Z variant and a novel shutter domain mutant (His334Asp; a 1 -antitrypsin King's) identified in a 6-week-old boy who presented with prolonged jaundice. His334Asp a 1 -antitrypsin rapidly forms polymers that accumulate within the endoplasmic reticulum and show delayed secretion when compared to the wild-type M a 1 -antitrypsin. The 2C1 antibody recognizes polymers formed by Z and His334Asp a 1 -antitrypsin despite the mutations directing their effects on different parts of the protein. This antibody also recognized polymers formed by the Siiyama (Ser53Phe) and Brescia (Gly225Arg) mutants, which also mediate their effects on the shutter region of a 1 -antitrypsin. Conclusion: Z and shutter domain mutants of a 1 -antitrypsin form polymers with a shared epitope and so are likely to have a similar structure. (HEPATOLOGY 2010;52:1078-1088 T he serpinopathies are conformational diseases characterized by the polymerization and intracellular retention of members of the serine protease inhibitor or serpin superfamily of proteins.1 The best known is a 1 -antitrypsin deficiency, with the most common severe deficiency allele being the Z mutation (Glu342Lys). This mutation results in the retention of ordered polymers of a 1 -antitrypsin as periodic acid Schiff positive inclusion bodies within the endoplasmic reticulum (ER) of hepatocytes.2 These inclusions predispose the individual homozygous for the Z variant of the a 1 -antitrypsin protease inhibitor (PI*Z) to neonatal hepatitis, cirrhosis, and rarely, hepatocellular carcinoma.3 Deficiency of circulating a 1 -antitrypsin results in early onset panlobular emphysema.

Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is an autosomal dominant dementia؊1 and 533.3 nM, respectively. An assessment by circular dichroism showed that S49P neuroserpin had a lower melting temperature than wild-type protein (49.9 and 56.6°C, respectively) and more readily formed loop-sheet polymers under physiological conditions. Neither the wildtype nor S49P neuroserpin accepted the P7-P2 ␣ 1 -antitrypsin or P14-P3 antithrombin-reactive loop peptides that have been shown to block polymer formation in other members of the serpin superfamily. Taken together, these data demonstrate that S49P neuroserpin is a poor proteinase inhibitor and readily forms loop-sheet polymers. These findings provide strong support for the role of neuroserpin polymerization in the formation of the intraneuronal inclusions that are characteristic of FENIB.

Aims: Early phagocytosis of glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes parasitized by Plasmodium falciparum were shown to protect G6PD-deficient populations from severe malaria. Here, we investigated the mechanism of a novel antimalarial series, namely 3-[substituted-benzyl]-menadiones, to understand whether these NADPH-consuming redox-cyclers, which induce oxidative stress, mimic the natural protection of G6PD deficiency. Results: We demonstrated that the key benzoylmenadione metabolite of the lead compound acts as an efficient redox-cycler in NADPH-dependent methaemoglobin reduction, leading to the continuous formation of reactive oxygen species, ferrylhaemoglobin, and subsequent haemichrome precipitation. Structure–activity relationships evidenced that both drug metabolites and haemoglobin catabolites contribute to potentiate drug effects and inhibit parasite development. Disruption of redox homeostasis by the lead benzylmenadione was specifically induced in Plasmodium falciparum parasitized erythrocytes and not in non-infected cells, and was visualized via changes in the glutathione redox potential of living parasite cytosols. Furthermore, the redox-cycler shows additive and synergistic effects in combination with compounds affecting the NADPH flux in vivo. Innovation: The lead benzylmenadione 1c is the first example of a novel redox-active agent that mimics the behavior of a falciparum parasite developing inside a G6PD-deficient red blood cell (RBC) giving rise to malaria protection, and it exerts specific additive effects that are inhibitory to parasite development, without harm for non-infected G6PD-sufficient or -deficient RBCs. Conclusion: This strategy offers an innovative perspective for the development of future antimalarial drugs for G6PD-sufficient and -deficient populations. Antioxid. Redox Signal. 22, 1337–1351.