Serum copper profile in patients with type 1 diabetes in comparison to other metals.

BACKGROUND: Type 1 diabetes (T1D) is a chronic condition in which the pancreas loses the ability to produce insulin due to an autoimmune destruction of the insulin producing beta cells in the pancreatic islets of Langerhans. Pathophysiological complications related to diabetes include micro and macrovascular disease, nephropathy, and neuropathy that can also be affected by environmental factors such as lifestyle and diet. OBJECTIVES: The current study aimed to evaluate the serum levels of total copper, the copper-carrying protein, ceruloplasmin and nonceruloplasmin bound copper (nonceruloplasmin-Cu) and other essential and environmental metals and metalloids in subjects with T1D compared with healthy controls. METHODS: A cohort of 63 subjects with T1D attending Diabetes Clinics at the University of Miami and 65 healthy control subjects was studied. Metals and metalloids were measured by inductively coupled plasma mass spectrometry. RESULTS: A main finding of this study was that total copper and ceruloplasmin levels were higher in persons with T1D compared to healthy controls. In comparison to other metals and clinical variables, elevated copper was the strongest factor associated with T1D resulting in a15-fold increased odds of having the disease per standard deviation increase. CONCLUSION: Our results suggest a metal and metalloid perturbation in T1D with a significant involvement of Copper dysfunction in the disease pathology, possibly linked to inflammatory processes.

Affinity purification of streptavidin using tobacco mosaic virus particles as purification tags.

A new protein affinity purification system has been developed. Recombinant tobacco mosaic virus (TMV) was used as an affinity matrix for isolation and purification of the given protein of interest. In model experiments, streptavidin-specific heptapeptide sequence TLIAHPQ was inserted into TMV coat protein near the C end. This oligopeptide did not interfere significantly with viral replication, assembly, and movement. Recombinant TMV functioned as an epitope tag recognizing streptavidin in plant protein extracts. Plant protein extracts containing streptavidin were incubated with recombinant TMV virions. Affinity complexes of viral particles with the protein of interest were collected by centrifugation. Recombinant TMV-streptavidin complex was dissociated with 0.2M acetic acid, pH 4.6, and was passed through membrane filter Nanosep 300K by centrifugation. The filtrate contained pure streptavidin. Recombinant TMV was left on the filter. TMV particles collected from the filter could be used for at least two more purification cycles. The streptavidin-specific recombinant TMV system was applied successfully for purification of streptavidin from Streptomyces avidinii. The authors believe that the TMV-based affinity system can also be used for the purification of other proteins.