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According to previous studies, ADP/ATP carrier (AAC) can possibly exist as a monomer or in a dimer state in the inner mitochondrial membrane; however, the question on its functional oligomeric state is still open. The aim of the present work is to establish the external factors that could control the functional oligomeric state of AAC (i.e., monomer or dimer). The study is based on the results of our previous work, which revealed that the volume regulation system of mitochondria (MVRS) affects the oxidative phosphorylation (OXPHOS) system: MVRS could transfer OXPHOS system functioning in a state of supercomplex. Consequently, one may expect that the volume regulation system could also control the functional state of AAC during phosphorylation. Here, on rat liver mitochondria we show that, depending on the incubation medium tonicity, AAC functions in two different ways: either as a monomer (in hypotonic and isotonic media) or as a dimer (in a hypertonic medium). Thus, the transition between the monomeric and dimeric forms of AAC is regulated by MVRS, as well as by functioning of OXPHOS. We conclude that the structural reorganization of AAC is associated with the entire OXPHOS reorganization into a supercomplex. It was also found that dimerization of AAC can occur not only due to the action of MVRS (in hypotonic media) but also under hypoxic conditions.

24 European Crystallographic Meeting, ECM24, Marrakech, 2007 Page s136 Acta Cryst. (2007). A63, s136 The structures confirm that the protein is also capable of binding these ligands in multiple copies, even though their molecular shapes and dimensions are different from zeatin. All these data suggest that PR-10 proteins can function as a reservoir for cytokinin molecules, maintaining high level of their availability and delivering them to their receptors.

The sucrose isomerase, MutB, from Pseudomonas mesoacidophila belongs to glycoside hydrolase family 13, and catalyzes the isomerization of sucrose into isomaltulose and trehalulose [1]. The 64 kDa enzyme has been crystallized [2] and the three dimensional structure of MutB has been solved to 1.6 A resolution by the molecular replacement method using the isomaltulose synthase, PalI, from Klebsiella sp. LX3 as a search model [3]. The overall structure of MutB is made up of three domains: an N-terminal and catalytic (β/α)8 domain, a subdomain and a C-terminal domain made up of seven β-strands [4]. The structures of various complexes with inhibitors and/or substrate analogues have been obtained and are currently under refinement. Once the detailed analyses of these structures have been completed, a better understanding of the molecular basis of sucrose decomposition, isomerization as well as the selectivity of this enzyme leading to the formation of different products should be gained.

In reporting this case it is not my object to go into a full description of the condition which existed up to the time of the puncture of the ventricle, but a few words will give a clearer insight into the condition which existed before the operation. History. —The patient, J. J. C., aged 16, was admitted, on Oct. 4, 1910, to St. Vincent's Hospital, New York, where I was then house surgeon, and a day or two later developed a typical case of cerebrospinal meningitis with classical symptoms. Examination of the spinal fluid corroborated the diagnosis. On admission the temperature was 105 F., pulse 90, respirations 26. Delirium developed in a few hours and continued up to the time of the operation, with short intermissions. The temperature fluctuated between 101 and 104 F. until October 20, when I opened the skull. From the date of admission, October 4, to