Compositions and methods for characterizing cancer cells by determining a marker of PGK1 activity. For example, methods are provided for predicting a patient response to a PGK1 inhibitor, a MEK/ERK inhibitor, an EGFR inhibitor, or a PIN1 inhibitor therapy. Methods for treating patients with such therapies are likewise provided.

Disclosed are methods and reagents for the enzymatic measurement of short-chain fatty acids, having 3 to 6 carbon atoms, in a sample. Methods include the use of recombinant butyrate kinases from multiple species, combined various reagents that includes ATP, to detect butyric acid in different types of samples via measurement of ATP consumption. Disclosed also are the reagents themselves.

Disclosed is an enzymatic measurement method comprising: contacting butyric acid in a sample, adenosine triphosphate (ATP), and butyrate kinase to produce adenosine diphosphate (ADP); and measuring the produced ADP.

Methods for detecting thyroid cancer or for differentiating malignant thyroid tissue from non-malignant thyroid tissue comprises measuring the amount of one or more of PGK1, PKM2, PTEN, Profilin-1, S100A6, Galectin-3 and Cyclin D1 and measuring under-expression or over-expression of these markers in comparison to normal tissue. The methods can be used with a fine needle aspiration biopsy (FNAB), a core biopsy or a cytosmear.

Provided in the present disclosure is a method for sequencing a double-stranded target polynucleotide. The method can keep ATP at a relatively constant concentration during sequencing, so that the sequencing rate can be better kept stable and unchanged. Further provided in the present disclosure is a kit for sequencing a double-stranded target polynucleotide, the kit including a transmembrane pore in the membrane, a helicase, an ATP-generating enzyme and an ATP-generating substrate.

Disclosed herein are methods and compositions for diagnosing cognitive fatigue. Specifically, the disclosure provides a method of diagnosing a subject as suffering from cognitive fatigue, which comprises measuring the amount of a biomarker, comprising phosphoglycerate kinase 1 (PGK1) and/or miR3185, in an exosome sample obtained from a saliva sample from the subject, comparing the amount with a control, and identifying the subject as suffering from cognitive fatigue.