{'fraction_non_alphanumeric': 0.03222748815165877, 'fraction_numerical': 0.0, 'mean_word_length': 4.932584269662922, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Fractionation of heparin by chromatography on a tissue plasminogen activator-Sepharose column.

Heparin stimulates the activity of tissue plasminogen activator (t-PA) and binds to t-PA. To study this interaction, a complex between t-PA and N-acetylated heparin was formed and then linked to Sepharose. This procedure selectively links the t-PA to the column because the acetylated heparin has no free amino groups. The procedure also protects the heparin-binding site(s) on the enzyme during coupling to the matrix. The t-PA column separates heparin into two fractions, one with low affinity for t-PA and one with high affinity. Both fractions of heparin effectively accelerate inactivation of thrombin by antithrombin III. However, the fractions differ in their ability to stimulate t-PA: the low-affinity heparin has no effect on the activity of t-PA, whereas the high-affinity heparin enhances this activity. These heparin fractions will be useful in characterizing the biochemical basis and physiological consequences of the heparin--t-PA interaction.