What is apparent from the experimental data is reduced protection in the hydrophobic core of Z a1AT. In fact, regions showing significantly increased exchange in Z a1AT form a nearly contiguous group that encompasses much of the core of the molecule. The exchange resistant core of M a1AT has previously been shown to consist of b-sheet rich regions. In M a1AT, peptic fragments that are protected from exchange include b2A, b3A-b4C, b2B-b3B and b6A-hI, and are described as showing class 3 exchange in figure 7. For Z a1AT only residues show significant protection with residues corresponding to b2A, b3A-b4C, b2B-3B and b6A-hI demonstrating class 2 behaviour. The peptide covering residues 227�C240 are heavily protected from exchange in both M and Z a1AT with less than 10% of the hydrogen available for exchange exchanging in the experimental time frame. This peptide, which has been identified in several previous studies as being resistant to chemical denaturation and has been proposed to play a role as folding initiator, remains unaffected by the Z mutation. The increased deuterium exchange seen for the ‘core’ peptides in Z a1AT may allow the molecule to sample conformations that on the folding pathway and lead to accumulation of the polymerogenic folding intermediate that the open sheet intermediate is on pathway and the loss of the salt bridge leads to enhanced lability and ability to switch to a polymerogenic conformation. In conclusion, our data clearly demonstrates that the single mutation Glu342Lys results in global dynamic changes to the Sibutramine HCl serpin fold. This in turns leads to an increase in the probability of Z a1AT sampling an open sheet structure capable of polymerisation. The widespread clinical use of antibiotics has induced rapid evolution of the amount and types of multidrug-resistant bacteria. Antibiotic resistance, which is acquired mainly by conjugative plasmid DNA transfer, is a threat to global health. In 2009, New Delhi metallo-b-lactamase, which confers high carbapenemase activity, was first detected in clinical samples from a Swedish patient of Indian origin in New Delhi, India. Bacteria carrying the NDM-1-encoding blaNDM-1 gene are resistance to a broad spectrum of b-lactam antibiotics, including carbapenems, which are frequently used to treat infections caused by antibioticresistant gram-negative bacteria. The lack of efficient drugs against multidrug-resistant pathogens poses a serious threat to public health. One feasible method to address this threat is to eliminate the drug-resistance plasmid, as such plasmids may be occasionally lost during natural reproduction or may be eliminated by exposure to physical or chemical treatments. Here, we characterized a NDM-1-producing A. calcoaceticus isolate from China using whole genome sequencing and plasmid elimination assays. Currently, the majority of NDM-producing Acinetobacter spp. have been isolated in China and the Estradiol Benzoate Middle East. Most of the isolates were identified as A. baumannii. Other NDMproducing Acinetobacter spp. have been identified in Chinese isolates, including A. pittii, A. lwoffii, and A. junii. In the present study, NDM-1-production in A. calcoaceticus was identified for the first time. The inappropriate use of b-lactamase antibiotics is causing an increasing public health threat of multidrug-resistant bacteria and poses a considerable challenge to the treatment of clinical infections. The development of appropriate methods to eradicate drug-resistant bacteria has become a focus of recent research.